The universe is ready for its close-up! That's because today marks the day that the Vera C. Rubin Observatory begins it's 10-year mission to shoot the greatest cosmic move ever created.

The decade-long project officially known as the Legacy Survey of Space and Time (LSST) is set to revolutionize our view of the universe. That means June 30, 2026 marks the beginning of a new era for astronomy.

"Today, we begin filming the greatest cosmic movie ever made," U.S. National Science Foundation (NSF) director Brian Stone said in a statement. "Every night, NSF–Department of Energy (DOE) Rubin Observatory will expand the frontiers of knowledge and strengthen America's global leadership in science and innovation."

The LSST will see Rubin use its 3200-megapixel camera, the largest digital camera ever created, to repeatedly scan the entire sky over the southern hemisphere every few nights. Over the next decade, each point in the sky will be covered 800 times; this will result in an ultra-wide, ultra-high-definition time-lapse record of the cosmos, the scale of which will put any Sci-Fi epic to shame.

And that includes the daring voyage of discovery present in any great Sci-Fi story. Astronomers teaming with Rubin will dive headfirst into the dark universe. That means the dual mysteries of dark energy — the force driving the accelerating expansion of the universe — and dark matter — which secretly seems to be holding galaxies together. Both are invisible to us, yet integral to the universe.

"With the launch of the ten-year Legacy Survey of Space and Time, NSF–DOE Rubin Observatory is opening a new window on the universe. It is embarking on a mission that will redefine modern cosmology and astrophysics," Darío Gil, Under Secretary for Science at the DOE said in the statement. “With its world-class design and tools, Rubin Observatory will capture the dynamic nature of our cosmos and reveal unimagined insights into our universe's biggest mysteries, from our own solar system to the very structure of the universe.

"By seeking to understand the enigmatic phenomena of dark energy and dark matter, we are not just observing the stars; we are striving to grasp the fundamental laws that govern our existence."

The main actors in this LSST production will be a cast of pulsating stars, supernova explosions and fossil records of galaxies. This will not only provide clues as to the nature of dark matter and dark energy, but could also reveal hitherto undiscovered cosmic phenomena.

Rubin will also make an impact on astronomy within the solar system, not just at the vast cosmic distances.

For instance, Rubin is expected to discover millions of new asteroids and comets in our cosmic backyard, becoming the most powerful solar system discovery machine ever created. It is already living up to this potential.

In its first few months of operations, Rubin, which sits atop a mountain in northern Chile, has already discovered 11,000 never-before-seen asteroids, including 33 near-Earth objects and 380 icy minor planets and dwarf planets out past the orbit of Neptune, referred to as trans-Neptunian objects.

It is estimated that the final LSST dataset will contain billions of objects, and its results will be available to all scientists and the general public — truly sparking a new age of cosmic discovery.

"It's taken 20 years of hard science, engineering, and more to get to the point where we can call 'action' as we start rolling on this blockbuster movie of the universe," Phil Marshall, Deputy Director of Rubin Operations for SLAC, said. "Millions of alerts in just the last couple of months show that Rubin is up and running as a discovery machine. Now we're putting it all together."

One of the most hotly debated mysteries in astronomy is set to continue, as new research fails to rule out self-annihilating dark matter as the source of gamma-ray emissions from the heart of the Milky Way. Known as the Galactic Center Excess, a spherical gamma-ray glow extending out for thousands of light-years from the core of our galaxy, this high-energy light has baffled researchers for over a decade.

While several possible explanations for the Galactic Center Excess have been put forward, including a population of rapidly spinning neutron stars called pulsars, one of the most prevalent has been a specific type of dark matter particle. Dark matter is the mysterious stuff that accounts for 85% of the universe's matter. It is effectively invisible because it doesn't interact with light or with "ordinary" matter composed of atoms. That fact has led to many possible dark matter candidate particles being proposed, including some that self-annihilate. This is akin to what happens when an electron meets its antimatter counterpart, or positron. The two annihilate each other, releasing energy into the cosmos.

For self-annihilating dark matter, these particles would be their own antiparticles, meaning when they interact, they would annihilate and release energy as gamma rays. With dark matter outweighing ordinary matter by a ratio of five to one, one might expect this annihilation to be occurring constantly, flooding the cosmos with gamma rays, but dark matter rarely interacts with itself in this model. Thus, dark matter annihilation is only a factor when this mysterious stuff is densely clustered in a region like the heart of a galaxy.

Unfortunately, investigating the heart of the Milky Way is challenging indeed.

"Interpreting the signal is particularly difficult because the Galactic Center is an exceptionally bright and crowded region of the gamma-ray sky," team member and University of Vienna researcher Florian List said in a statement.

Getting to the point

To investigate if annihilating dark matter could indeed account for the Galactic Center Excess, List and colleagues turned to machine learning trained on more than a million simulated gamma-ray observations. Previous similar approaches had pointed to comparatively bright, unresolved light sources as a potential source of the Galactic Center Excess. However, this new research showed that these point sources, including pulsars, would be extremely faint, and that is good news for scientists who favor annihilating dark matter as the cause of these gamma rays.

That is because, whereas previous research has suggested just a few hundred pulsars could be enough to account for the Galactic Center Excess, these findings indicate that the pulsar population at the heart of the Milky Way would have to be greater than 35,000.

"Our new analysis shows that the sources would have to be so faint that they would be almost indistinguishable from the emission expected from annihilating dark matter," team member Nick Rodd, a scientist at the Lawrence Berkeley National Laboratory, said.

While this research may keep dark matter in the game as a plausible explanation, it far from confirms the annihilation of this mysterious stuff as the source of the Galactic Center Excess. "The origin of the Galactic Center Excess is one of the longest-running debates in astrophysics," List said. "Our work does not show that dark matter is responsible for the signal. However, it suggests that it is still too early to rule out this possibility."

The team's research was published on Thursday (Feb. 5) in the journal Physical Review Letters.

Astronomers have used a technique called echo mapping to detect hints that supermassive black holes, such as the cosmic titan at the heart of the Milky Way, known as Sagittarius A* (Sgr A*), are surrounded by dense clouds and clusters of dark matter. The research could teach us more about this mysterious substance and the environments around supermassive black holes.

Dark matter is the universe's most mysterious stuff, outweighing ordinary matter in the cosmos by a ratio of five to one — but remaining effectively invisible because it doesn't interact with electromagnetic radiation, including the light we use to see. The only way scientists can even infer the presence of dark matter is via its interaction with gravity, and the impact that this interaction has on objects made of traditional matter like stars. For instance, the gravitational effect of dark matter allows stars at the edges of galaxies to whip around at much greater speeds while not flying loose than the visible matter of those galaxies would allow.

This team decided to test the gravitational influence of dark matter at the hearts of galaxies, environments dominated by supermassive black holes which can have masses millions or even billions of times that of the sun. Ordinary matter around these supermassive black holes is often very visible, especially when spiraling into the maw of one of these cosmic titans from a flattened cloud called an accretion disk. This is because the gravitational influence of those black holes generates immense amounts of friction, causing them to grow brightly. That wouldn't work for dark matter; it can't feel friction because it doesn't interact with itself or with ordinary matter, and it can't glow because it doesn't absorb or emit light.

Clearly, dark matter can't be spotted around supermassive black holes even using the most advanced telescopes such as the Event Horizon Telescope (EHT), which has captured glowing rings of material around Sgr A* and around a more distant supermassive black hole that rules the heart of the galaxy Messier 87 (M87).

While discussing the problem of detecting dark matter around supermassive black holes, Mayank Sharma, a physics graduate student at Virginia Polytechnic Institute and State University (Virginia Tech), hit on an interesting solution.

"We could actually test this prediction using a technique in astronomy, which allows you to measure the distance to the surrounding gas by looking for echoes of light," Sharma said in a statement. The technique Sharma refers to is "reverberation mapping," and it has become a trusted method of determining the mass of black holes.

Echoes of dark matter

Reverberation mapping is based upon the fact that as matter falls into a black hole, it releases a burst of energy that causes the accretion disk it comes from to pulse. This pulse of light travels from the accretion disk to gas in the wider environment of the black hole. This gas absorbs that light and also pulses, with this secondary pulse serving as an echo of the first.

Because we know the speed of light, when astronomers see the first pulse of light and then its echo, they can use the time between pulses to estimate the distance between the black hole and the gas on the outskirts of its environment. The size of a black hole and the distance between it and outer gas clouds can be used to determine its mass, and could also be used to determine the mass of dark matter clustered around it.

The team applied their method to 14 different galaxies, finding in five cases that mass increases moving away from the central black hole in a way that couldn't be accounted for by visible matter alone. Despite the early success of this research, it far from proves that supermassive black holes are indeed gathering places for dark matter. The team's findings do point an interesting way forward for the investigation into the universe's most mysterious substance and its most mysterious regions.

"These galaxies are definitely showing a hint that there is extra material that cannot be explained by just the supermassive black hole," Sharma said. "The prospects are exciting."

The team's research was published in the journal Physical Review D.

For decades, scientists have searched for a fifth fundamental force of nature that can explain mysterious aspects of the universe such as dark energy and dark matter. These are pieces of our cosmos that simply can't be accounted for by the four fundamental forces we know of: gravity and electromagnetism as well as the strong and weak nuclear forces.

In addition, while the hunt for this force has been ongoing, researchers have also been desperately hunting for a theory of quantum gravity. That's because quantum gravity can unite the best description we have of the universe on large scales — Albert Einstein's theory of general relativity — and the physics of the subatomic, aka quantum mechanics. Both theories emerged at the start of the 20th century and have been experimentally confirmed time and time again, yet they steadfastly refuse to overlap in a single unified theory.

But now, these two scientific quests have overlapped. New research built a quantum gravity framework — finding that it actually offers clues about potential fifth fundamental forces of nature.

The team's findings reveal that not all potential suggestions for a fifth fundamental force, which would manifest as a small deviation from Isaac Newton's law of gravitation at very small distances and would be described by two parameters: its strength and the range it acts over. In essence, the research could narrow down the search for a fifth fundamental force.

"One of the main challenges was overcoming a primarily conceptual obstacle: quantum gravity is often seen as an extremely abstract topic, almost impossible to connect to observable phenomena," Alfio Bonanno of the National Institute for Astrophysics (INAF) said in an emailed statement translated from Italian. "In some ways, it's like standing in front of a mountain face that everyone considers unscalable. The first step isn't technical, but mental: convincing yourself that a possible path actually exists. This work stems precisely from this idea: seeking a concrete connection between the physics of infinitesimally small scales and phenomena potentially observable in the real world."

The framework of quantum gravity explored by the team is called "asymptotic safety," which asserts that gravity can remain consistent and controlled even at high energies thanks to a halting in the strength of gravitational pull. If this theory is to remain valid at high energy levels, Bonanno and colleagues found that the range and strength of a fifth fundamental force were limited, resulting in an excluded region of these parameters.

"The most exciting aspect is that part of the theoretically excluded region has not yet been explored experimentally," Bonanno said. "This means that future high-precision measurements of gravitation could directly test — and potentially falsify — this class of quantum gravity-inspired models."

Usually, physicists hypothesize new forces and then determine if they could be detected by experiment; this research takes a different approach by ruling out certain possibilities for the characteristics of a proposed force. The fact that much of the region excluded by the team hasn't been explored experimentally lays the groundwork for making precise measurements of gravity to test quantum gravity.

"Our study shows that quantum gravity may not only be a valid theory at extreme and unattainable energies, but may also have concrete and testable consequences at much larger scales," Emiliano Glaviano of the INAF said in the statement. "The physics of infinitesimally small distances could leave observable traces in the macroscopic world: some possible new forces of nature would be ruled out not by experiments, but directly by the fundamental laws of the theory."

This research applies to physics on the tiny scales of quantum physics, where quantum gravity should emerge, to the scales of planetary objects. Thus, traces of this quantum gravity theory or a fifth fundamental force appearing as deviations from Newton's laws should be testable with a wide range of experiments. That includes using a technique called atomic interferometry or quantum sensors to make measurements across the solar system, such as lunar laser ranging, or on wider astronomical scales such as measuring the dynamics of planets.

The team's research was published in the May edition of the journal Physical Review Letters.

The most mysterious and yet ubiquitous stuff in the cosmos, dark matter is effectively invisible. This is simply because it doesn't interact with light. But what if instead of trying to see dark matter, scientists attempted to hear it instead?

New research suggests dark matter could leave a tiny but discernible imprint in the cacophony of ripples in spacetime called "gravitational waves" that ring through the cosmos when two black holes slam together and merge. However, this is only if spinning black holes can "churn" dark matter like cosmic butter. (We'll get to that shortly.)

The team behind this new research suggests that if two black holes merge in a region of space populated by dense dark matter clouds, then the gravitational waves emerging from the event could carry the imprint of dark matter across the universe. And it's possible, they say, that our detectors could find that imprint. This would be akin to someone coughing at a Metallica concert, and that cough being only discernible over the fury of "Seek and Destroy" or "Master of Puppets" with the most sensitive instruments.

Fortunately, when it comes to detecting gravitational waves from colliding black holes, humanity's instruments, such as LIGO (Laser Interferometer Gravitational-Wave Observatory), are getting more and more sensitive all the time. And in preparation for a time when such imprints could become even more easily logged in gravitational wave data, this team developed a method that predicts just what shape a gravitational wave should take when moving through dark matter, rather than empty space.

"Using black holes to look for dark matter would be fantastic," team member Rodrigo Vicente, a researcher at GRAPPA (Gravitation Astroparticle Physics Amsterdam), said in a statement. "We would be able to probe dark matter at scales much smaller than ever before."

I can't believe it's not butter

Dark matter represents such a puzzle because, despite being invisible to us, it still "outweighs" ordinary matter by a ratio of about five to one.

Its lack of interaction with light means it can't be composed of protons, neutrons and electrons — the particles that compose atoms. That's because atoms compose all the "ordinary matter" we see around us, from stars and planets to the device you're reading this article on and our own bodies. In other words, atoms do interact with light (more technically, electromagnetic radiation). In fact, the only way astronomers know dark matter exists is via its interaction with gravity and the way this interaction curves spacetime, indirectly influencing ordinary matter and light.

With this knowledge, scientists have been hunting for particles outside the Standard Model of particle physics that could account for dark matter. These particles have a wide range of potential masses and properties, with one hypothetical particle being the "light scalar" proposed to have a mass much smaller than that of an electron. One characteristic of the light scalar would be the fact that dark matter composed of these particles would act like coordinated waves around black holes.

Around a spinning black hole, rotational energy would be transferred to light scalar dark matter, amplifying its density, almost like a paddle churning cream into butter. If this dark matter "butter" gets dense enough, it could affect gravitational waves from merging black holes, leaving a telltale imprint.

After determining what this signature would look like, Vicente and colleagues searched through data gathered by LIGO and its fellow gravitational wave detectors, KAGRA (Kamioka Gravitational Wave Detector) and Virgo, focusing on 28 of the clearest signals from merging black holes. Of these, 27 appeared to have come from mergers that occurred in the relative vacuum of space. One signal, however, GW190728, first heard on July 19, 2019, and the result of merging binary black holes with a combined mass of 20 times that of the sun and located an estimated 8 billion light-years away, seemed to carry the telltale trace of this merger occurring in a region of dense, "buttery" dark matter.

The team behind this research is quick to point out that this can't be considered a positive detection of dark matter, but does say it gives us a hint at what to look for and thus where to direct follow-up investigations — something that could be increasingly useful as dark matter detectors on Earth continue into their fifth operating run with boosted sensitivity.

"We know that dark matter is around us. It just has to be dense enough for us to see its effects," said team leader Josu Aurrekoetxea, of the Massachusetts Institute of Technology (MIT) Department of Physics. "Black holes provide a mechanism to enhance this density, which we can now search for by analyzing the gravitational waves emitted when they merge."

The team's results were published on Tuesday (May 12) in the journal Physical Review Letters.

A new type of self-interacting dark matter could provide solutions to three very different cosmic puzzles, new research suggests.

The first mystery that could be solved involves an ultradense clump of matter detected in the system JVAS B1938+666, which is gravitationally lensed, or visibly distorted, thanks to a quirk of general relativity. The second has to do with a visible "scar" in a stream of stars called GD-1. It basically looks like a dense, invisible object ripped through the stream. And finally, there is the confusing formation of an unusual star cluster named Fornax 6 in the Fornax satellite galaxy of the Milky Way, which could have occurred if a dense patch of dark matter acted as a gravitational trap capturing passing stars.

The new research argues that if dark matter interacts with itself, that could explain away all three of these unique situations." What's striking is that the same mechanism works in three completely different settings — across the distant universe, within our galaxy, and in a neighboring satellite galaxy," Hai-Bo Yu of the University of California, Riverside and the Center for Experimental Cosmology and Instrumentation, said in a statement. "All show densities that are difficult to reconcile with standard model dark matter but arise naturally in self-interacting dark matter."

But what does it really mean for dark matter to "interact" with itself, and why would that be a deviation from the "standard" picture of this mysterious substance?

Anti-social dark matter can't explain these mysteries

First, let's go through a quick recap of what dark matter really is.

Dark matter accounts for around 85% of the matter in the universe, meaning it "outweighs" the ordinary matter that comprises stars, planets, moons, and our bodies by a ratio of around five to one. Scientists know dark matter can't be made up of protons, electrons and neutrons that compose the atoms that make up everything we see around us, because those particles interact with light (more accurately, electromagnetic radiation) — and whatever composes dark matter doesn't.

This also means dark matter is effectively invisible to us, only detectable via its interaction with gravity and the knock-on effect this has on everyday matter and light. Separately, the best theory of cosmic evolution we have so far is the standard model of cosmology, also known as the lambda cold dark matter (LCDM) model. In the LCDM model, dark matter is "cold," meaning its particles move slowly and don't collide when they meet, instead passing through each other without interacting like anti-social cosmic ghosts.

Thus, unlike cold dark matter, self-interacting dark matter particles can collide with each other, exchanging energy and momentum. These interactions can result in so-called "gravothermal collapse," creating dense, compact cores of dark matter.

"The difference is like a crowd of people who ignore each other versus one where everyone is constantly bumping into one another," Yu said. "In self-interacting dark matter, these interactions can dramatically reshape the internal structure of dark matter halos. Dark matter that interacts with itself can become dense enough to explain these observations."

"The difference is like a crowd of people who ignore each other versus one where everyone is constantly bumping into one another," Yu said. "In self-interacting dark matter, these interactions can dramatically reshape the internal structure of dark matter halos."

In short, this recipe of self-interacting dark matter allows for dense dark matter cores with morphology that could explain the strange aspects of the astronomical bodies such as the ultradense clump of matter observed in JVAS B1938+666 and the "scar" of GD-1 — but non-interacting dark matter can't. "Dark matter that interacts with itself can become dense enough to explain these observations," Yu added.

The team's research was published on April 9 in the journal Physical Review Letters.

Astronomers have unveiled one of the largest cosmological simulation datasets ever created, offering an expansive new tool to explore how the universe evolved across billions of years.

Produced by the FLAMINGO project — short for Full-hydro Large-scale structure simulations with All-sky Mapping — the dataset contains more than 2.5 petabytes of data, an amount researchers say is roughly equivalent to half a million HD movies. The sheer scale of the release reflects a growing need in astronomy: matching increasingly precise observations with equally sophisticated theoretical models, according to a statement from the Netherlands Research School for Astronomy (NOVA).

Modern telescopes and sky surveys are capturing the universe in extraordinary detail, but interpreting that data requires simulations that can reproduce both the large-scale structure of the cosmos and the complex physics unfolding within galaxies. FLAMINGO was designed to bridge that gap.

"These simulations allow us to follow the growth of cosmic structure across vast regions of space, while still modelling the complex physics of galaxy formation," Joop Schaye, co-author of the study from Leiden University, Netherlands, said in the statement. "By making the data publicly available, we hope researchers worldwide will use FLAMINGO to test new ideas about how the universe works."

The simulations function as "virtual universes," beginning shortly after the Big Bang and evolving forward in time. They track how tiny fluctuations in matter gradually grew into galaxies, clusters and the vast cosmic web that defines the large-scale structure of the universe today. What sets FLAMINGO apart from many earlier efforts is its ability to model not just dark matter — which makes up most of the universe's mass — but also ordinary matter and the effects of dark energy in a single, self-consistent framework, according to the study.

That combination allows scientists to study how processes on vastly different scales interact. The same simulation can capture the turbulent physics of gas forming stars inside galaxies while also mapping the distribution of galaxy clusters across billions of light-years. In turn, this helps researchers more accurately reproduce the observable universe.

The dataset's enormous volume also makes it especially powerful for studying rare phenomena. Massive galaxy clusters, luminous quasars and other uncommon cosmic objects are difficult to capture in smaller simulations simply because they occur so infrequently. FLAMINGO's scale increases the odds of finding these outliers, giving scientists a better understanding of some of the universe's most extreme environments.

Beyond individual discoveries, one of the project's most important roles will be helping astronomers interpret incoming data from next-generation observatories. As new surveys map the sky in unprecedented detail, researchers will need robust theoretical frameworks to compare against their observations. Simulations like FLAMINGO provide that context, allowing scientists to test competing models of dark matter, dark energy and galaxy formation.

The team has made the dataset publicly available, opening it to researchers around the world. That accessibility is key as astronomy becomes increasingly data-driven, with collaborations often spanning continents and relying on shared computational resources.

"Open access to datasets of this scale can significantly accelerate scientific progress," Matthieu Schaller, co-author of the study from Leiden University, said in the statement. "We aim to provide a resource that will support a wide range of astrophysical research."

Ultimately, FLAMINGO represents a shift in how scientists study the cosmos. Rather than relying solely on observations, researchers can now experiment within detailed virtual universes — adjusting physical assumptions, testing predictions and uncovering patterns that might otherwise remain hidden.

The FLAMINGO simulations data release was submitted to Astronomy & Computing on April 28 and is available on the arXiv preprint server.

In its infancy, the universe had a bit of an identity crisis.

For the first few hundred million years, the vast cosmic gas between galaxies was primarily a chilly, dense affair. But then, it seemed to wake up, deciding to get all warm and fuzzy.

This strange shift in the cosmos’ early disposition is a crucial clue to how the very first galaxies burst into being, shaping everything we see today. The early universe, a mere whisper after the Big Bang, just a few hundred million years old — that's when the first stars and galaxies were starting to flicker on, like fairy lights across a cosmic dark.

The fuel for all this grand production: gigantic clouds of gas, mostly hydrogen. Astronomers have always suspected these baby galaxies were busy, but new glimpses from the James Webb Space Telescope are showing them to be even brighter and larger than our wildest dreams. They're like finding teenagers sitting in a kindergarten class, way ahead of their expected development.

This cosmic precociousness means our existing models of how galaxies form might need a serious tune-up. We thought we had a pretty good handle on how gas falls into dark matter halos, cools down, and then ignites into stars. But the JWST data suggests a much more aggressive, faster-paced star-making frenzy in those early days. The question becomes: How did these young galaxies manage such a booming business so quickly?

To untangle this mystery, Umberto Maio from the INAF-Italian National Institute of Astrophysics and the Institute for Fundamental Physics of the Universe, working with Céline Péroux at the European Southern Observatory, decided to dive into the virtual cosmos. They created incredibly detailed computer simulations, a sort of cosmic time machine called ColdSIM, to rewind the clock and watch how gas behaved in the first billion years after the Big Bang. Their goal was to make predictions about the early universe’s baryon budget — that's the accounting sheet for all the "normal" matter, the stuff stars and planets are made of, and where it ended up.

What they found was a universe in flux. Before a pivotal moment called the epoch of reionization — when the universe finally became transparent to ultraviolet light — the gas was indeed mostly cold. It was the perfect, dense environment for star formation. But as star formation really picked up, and that intense ultraviolet light started zipping around, things changed. The simulations showed that the gas quickly shifted, becoming dominated by a warm, less dense phase. It’s like the universe went from a quiet, cool morning to a bustling, sun-drenched afternoon, with all that energy from new stars and radiation heating things up.

This wasn't just a minor temperature change. It fundamentally altered the rhythm of galaxy evolution. The team's clever simulations traced the journey of various types of gas, carefully avoiding the usual shortcuts in models that can often lead to fuzzy answers. They found some eye-opening things about how these infant galaxies put themselves together.

For starters, the stellar return fraction was surprisingly low. This is the amount of material that stars eject back into the surrounding gas when they die, essentially recycling fuel for the next generation of stars. In the early universe, it seems, stars were less efficient at this recycling. Lower quantities of old stellar material returned to the gas, meaning that new stars largely formed from fresh, pristine gas constantly falling in from the cosmic web. It's a bit like a construction site that keeps getting new materials delivered rather than reusing much from demolished buildings.

But even with less recycling, these galaxies were burning through their gas at an astonishing rate. Maio and Péroux discovered that the depletion times — the time it would take for a galaxy to convert all its gas into stars at its current rate — were incredibly short. Much shorter than we see in galaxies today. This means that early galaxies were true star-forming machines, gobbling up gas and spitting out stars with a furious intensity. It paints a picture of baby galaxies throwing one heck of a tantrum, furiously making stars with every available bit of gas.

So, why does any of this matter? Because it rewrites a part of our cosmic origin story. Our initial predictions for these early galaxies, based on observations of later, more mature galaxies, simply weren't capturing this dynamic, rapidly evolving picture. It turns out that you can't just take what you know about middle-aged galaxies and apply it to their energetic youth. The physical processes, from gas dynamics to stellar feedback, are just too different when the universe itself is so young and compact.

Of course, this cosmic detective story is far from over. Numerical simulations are powerful, but they’re always battling with the sheer complexity of the universe. Modeling everything from the intricate, multi-phase structure of gas to the powerful winds blown out by massive stars and black holes is a huge challenge. There are still big uncertainties, like the exact initial mass function of stars (how many big stars versus small stars are born) and the precise amount of "metals" needed to kickstart cooling. Our models still have plenty of room to grow.

But the good news is, we’re armed with ever more powerful tools. The James Webb Space Telescope is out there, giving us sharper and sharper images of these distant, ancient galaxies. And coming down the pipeline are next-generation radio telescopes, like the Square Kilometer Array (SKA), which will let us peer even deeper into the cold gas reservoirs of these early galaxies. These new eyes on the sky will give us the crucial real-world data needed to test these new theoretical predictions, helping us refine our models and paint an even clearer picture of the universe's chaotic, yet beautiful, beginnings.

The journey to understand how the universe built itself, one galaxy at a time, is still unfolding before us.

New research suggests that supermassive black holes that existed before the cosmos was 1 billion years old may have formed with a helping hand from dark matter, the universe's most mysterious stuff.

Ever since the James Webb Space Telescope (JWST) first began reporting data back to Earth in the summer of 2022, it has been delivering a curious problem into the laps of scientists, finding supermassive black holes as early as 500 million years after the Big Bang. That is, however, an issue because the merger and feeding processes that allow black holes to reach masses of millions of billions of times that of the sun should take at least 1 billion years to reach fruition.

Scientists have therefore been eagerly searching for a growth mechanism that could explain how supermassive black holes could exist so early in the universe. Now, one team of researchers theorizes that such cosmic titans could have come about before their time, thanks to changes made to galaxies by energy released by the decay of dark matter.

One suggested mechanism for the early growth of black holes is the direct collapse of vast clouds of gas and dust to immediately form a seed black hole without the time it takes for a massive star to be born, live its life, and then die.

However, that process would still require stars shining on these clouds of matter, providing them with energy — but that's rare. Too rare to explain the abundance of early supermassive black holes seen by JWST. That is, unless there is another energy source to help this process along.

"Our study suggests that decaying dark matter could profoundly reshape the evolution of the first stars and galaxies, with widespread effects across the universe," team leader Yash Aggarwal of the University of California, Riverside, said in a statement. "With the JWST now revealing more supermassive black holes in the early universe, this mechanism may help bridge the gap between theory and observation."

Does dark matter decay?

Dark matter is the mysterious substance that makes up 85% of the matter in the cosmos. It remains so curious because it doesn't interact with light (more accurately, electromagnetic radiation). Not only does this make it effectively invisible, but it also tells scientists that dark matter can't be made up of electrons, neutrons and protons, the particles that compose the atoms that make up stars, planets, moons, our bodies and everything we see around us.

This has spurred the search for particles beyond the Standard Model of particle physics. These hypothetical particles have a range of masses and possible properties. This includes some that pass through each other like ghosts, some that interact with each other, exchanging energy, and others that decay into smaller particles, releasing a tiny bit of energy in the process.

Aggarwal and UCR colleague Flip Tanedo think that it would only take energy equivalent to a billion trillionth of the energy of a single AA battery to "supercharge" primordial gas clouds, with the decay of dark matter capable of providing this.

"The first galaxies are essentially balls of pristine hydrogen gas whose chemistry is incredibly sensitive to atomic-scale energy injection," said Tanedo. "These are the properties that we want for a dark matter detector — the signature of these 'detectors' might be the supermassive black holes that we see today."

The team's work also allowed them to pin down a hypothetical mass range of between 24 and 27 electronvolts for dark matter particles capable of sparking the creation of direct collapse black holes that could give supermassive black hole growth a head start. The team's conclusion stems from a series of very happy coincidences that help them gather the right mix of particle physicists, cosmologists and astrophysicists to formulate a theory of cosmic coincidence.

"We showed that the right dark matter environment can help make the 'coincidence' of direct collapse black holes much more likely," Tanedo said. "In the same way, the support for interdisciplinary work helped make the 'coincidence' leading to this work possible."

The team's research was published on Tuesday (April 14) in the Journal of Cosmology and Astroparticle Physics.

GREENBELT, Md. — On Tuesday (April 21) here at NASA's Goddard Space Flight Center, I watched as scientists stood proudly around a metal contraption with towering orange solar panels and a sparkling silver base. Gleaming right before me in a sterile white clean room stood the Nancy Grace Roman Space Telescope — at last, complete.

"I very much hope, and in fact, expect, that the most exciting science from Roman is going to be the things that we didn't expect, that we couldn't predict, but that will set the new deep questions for future missions to address," Julie McEnery, senior project scientist of Roman said during a press conference on Tuesday.

Named for NASA's first chief of astronomy and the first woman to hold an executive position at the agency, this space telescope should turn out to be yet another valuable tool in our species' hunt to understand the true nature of the universe. It'll stand among the ranks of our other powerful robotic eyes on the sky — famed instruments like the James Webb Space Telescope (JWST), SPHEREx, the Euclid Space Telescope and even the aged but always impressive Hubble. Except, as is the case with each of those landmark observatories, this new one has its own specialty. We'll get into some of those specs soon.

Above all, now projected to launch in September 2026 — eight months ahead of schedule, and under budget — the Nancy Grace Roman Space Telescope (or "Roman" for short) has the potential to show us pockets of the cosmos we've yet to touch.

According to NASA, Roman's primary mirror measures about 7.9 feet (2.4 meters) wide, which is similar to Hubble's. However, Roman has the ability to take images that capture a patch of the sky at least 100 times larger than Hubble can.

"Its surveying capabilities are over 1,000 times faster than Hubble, and can chart 200 times more sky in a single image," NASA administrator Jared Isaacman said during the conference. "What would take Hubble 2,000 years to process, Roman can do in a year — the images it captures will be so large there is not a screen in existence large enough to show them."

To put that into context, over its approximately 35 years of service so far, Hubble has gathered about 400 terabytes of data; once fully operational at its workstation in space, Roman should be able to create 500 terabytes of data per year.

As for what this data could hold, well, the possibilities are pretty endless. That's typically the gold standard for a telescope; as scientists like to say, we're always hoping to answer questions we never even thought to ask.

Cosmic and panoramic

Roman is specifically calibrated to capture images of the universe in visible and near-infrared light. Different telescopes view the universe in different light wavelengths. The JWST, for instance, specializes in infrared observations, while Hubble's powers allow it to see some infrared but mostly visible and ultraviolet light.

Diversifying in this way is important, because you can think of a patch of sky as having various layers. As an example, many extremely distant objects can be seen only in infrared light — which consists of super-long wavelengths that aren't visible to the human eye — so you need an infrared telescope to decode that layer. But there are also visible-light objects in the same patch of sky that need to be studied in greater detail, for which you need a telescope that behaves like an ultrapowerful human eye. And so on.

A few things set Roman apart, including that quick data-processing speed we discussed earlier.

Compared to the JWST, Roman's images — taken with its aptly named Wide Field Instrument (WFI) — will be 50 times wider but more shallow, because Roman doesn't need to access the deep universe the way the JWST does. As we discussed, it can't see infrared like the JWST can and therefore would be wasted in looking too far back.

More specifically, WFI is composed of a 300-megapixel visible-to-near-infrared imaging camera and slitless spectrometer (a special tool that allows scientists to capture light dispersion of objects in a field of view). But there is something uniquely special about that shallow, panoramic view.

It means scientists don't have to be as picky about which patch of sky they're looking at. They can just survey and hope to find a cool lead to zoom in on. This offers Roman the ability to catch events that transpire very quickly, such as fast radio bursts, and increases the chances that scientists can witness remarkable supernovas, colliding neutron stars and other easy-to-miss phenomena right as they happen.

"So we're going to see thousands of supernovae, and some of these are going to be further away than any supernovae we've ever seen before," Dominic Benford, program scientist for the Nancy Grace Roman Telescope told Space.com. "We'll trace the history of the universe through exploding stars."

There is also the hope that Roman helps us unravel one of the greatest mysteries of our universe — the details of its dark side.

The dark and faint universe

Despite years upon years of searching for an answer, scientists still don't know what exactly dark matter and dark energy are. All we know so far for sure is that our universe's normal matter does not appear to be enough to prevent galaxies from falling apart like horses on a merry-go-round that isn't nailed together properly, and that the universe is also accelerating in its continuous expansion far faster than seems normal. The former is explained by a substance called "dark matter" picking up where normal matter leaves off, and the latter is explained by "dark energy" driving that expansion.

These two substances collectively constitute 95% of the universe yet have never been detected with certainty. It's absolutely bizarre, if I may say.

Of course, with that kind of track record, it can't be known for sure whether Roman will suddenly reveal what the dark universe actually is — but if all goes to plan, we can expect it to bring us quite a bit closer.

Thanks to that lovely wide field of view, Roman will be able to rapidly image tons of galaxies to generate detailed, 3D vistas of the cosmos. It will therefore be able to show us things like the dynamics of different galaxies and track the universe's expansion — the two main ways we investigate dark matter and dark energy.

"We'll also study how the universe itself has expanded over time. And these are the keys to unlocking the fundamental nature of dark matter, dark energy, the fabric of the universe itself," McEnery said.

And that's not to mention what the Roman's other special instrument suite can do for science. For example, it has a coronagraph, a tool that can block the glare of distant suns and help the mission directly image exoplanets. In fact, NASA says this telescope's coronagraph can detect planets 100 million times fainter than their stars. That capability is about 100 to 1,000 times better than existing space-based coronagraphs, the agency explains in an overview.

"The Roman Coronagraph will be capable of directly imaging reflected starlight from a planet akin to Jupiter in size, temperature, and distance from its parent star," that overview states.

Road to launch

Now that Roman is complete, the next phase of its journey can soon commence. That'll include being shipped to the launch site, NASA's Kennedy Space Center in Florida, and undergoing any necessary launch-related testing.

A hefty amount of prelaunch testing has already been conducted on Roman so far, including the poor observatory being blasted with extreme sounds, being shaken up to an extreme degree, being exposed to extreme heat and extreme cold — and way more (all just as extreme). Sounds rough, but the point is to make sure Roman will be able to handle the rigors of launch and the most extreme environment we know of: space.

"Most of the stuff that's left are the final checkouts, and the final wrap-ups," Jeremy S. Perkins, Observatory Integration and Test Scientist for Roman, told Space.com "There is lots of blanket close-outs and making sure that we've put all the sensors on and taken off the ones that were there for testing."

As for launch procedures, once all aspects of testing are squared away, NASA has chosen a SpaceX Falcon Heavy rocket to carry this treasure to space. There have been 11 Falcon Heavy launches to date, with a 100% success rate for the 230-foot-tall (70-meter-tall) vehicle.

Once in space, after separating from that rocket, Roman will head to a stable point about a million miles away from Earth called Lagrange Point 2, or L2. This is a popular spot for our space explorers to end up because it allows them to remain shielded from the sun's heat while still orbiting in such a way that mission control can communicate with them easily.

Hopefully the JWST, Euclid and the rest of the L2 crew welcome Roman with open arms (solar panels?).

Correction 4/21: Julie McEnery's name has been updated to reflect the correct spelling.

Our universe is full of mysteries, but few are as perplexing as the dark, tiny galaxies that hover around larger ones like the Milky Way.

Small, dim, and almost invisible, dwarf spheroidal galaxies are packed to the brim with something we can't see: dark matter. They're like cosmic icebergs, with most of their mass hidden from plain sight, making them some of the most exotic objects in the universe.

But these deceptively simple structures hide a deep secret. For years, astronomers have scratched their heads over a thorny problem, often called the "cusp-core problem." Our best theories for dark matter, based on the cold dark matter model, predict that the density of this invisible stuff should get incredibly steep, forming a "cusp" at the very center of these galaxies. Like a mountain peak, sharp and pointy, where dark matter congregates.

Yet, when we peer at the actual movements of stars inside many of these dwarf galaxies, what we often see is something flatter, more like a gentle hill – a "core." It’s a bit like finding a perfectly smooth, inviting plateau where you expected a jagged, impassable summit. This persistent mismatch has fueled a serious debate, leaving us wondering if our understanding of dark matter, or perhaps galaxy formation itself, is fundamentally off.

This mystery has challenged the standard picture of how galaxies form and evolve. But astronomers are clever, and they keep digging. Consider this: these galaxies aren't just born with their final shape, but instead evolve into it, following a cosmic blueprint. This is the idea at the heart of new research from Jorge Peñarrubia and Ethan O. Nadler, affiliated with the Institute for Astronomy at the University of Edinburgh and the Department of Astronomy & Astrophysics at the University of California, San Diego. They propose that dwarf spheroidal galaxies are always moving toward a specific, stable configuration, a cosmic resting place they call a "dynamical attractor." It's like every tiny galaxy has a pre-determined final form, and no matter its starting conditions, it's destined to build itself into that design.

How does a galaxy find its way to this precise blueprint? It's not a gentle drift toward equilibrium. Stars inside these dwarf galaxies get a constant, chaotic cosmic kick in the pants. They don't just orbit smoothly around the galaxy's center, like planets around a star. Instead, they’re constantly jostled by what Peñarrubia and Nadler describe as "stochastic force fluctuations." Think of it like a pinball machine. The stars are the pinballs, and instead of perfectly smooth walls, they're continually bumping into invisible, unpredictable bumpers, always gaining a little bit of energy.

What are these invisible bumpers? They are "dark subhaloes" — clumps of dark matter embedded within the galaxy's larger, smoother dark matter halo. Yes, even within the mysterious dark matter, there are smaller, lumpier bits. Causing trouble. These dark subhaloes exert unpredictable gravitational forces, giving energy to the stars and pushing their orbits outward. The stars gain energy, their orbits expand, and the entire stellar system starts to puff up and spread out. This process, in which stellar orbits expand and gain energy, is a kind of internal "heating" for the galaxy, driving its evolution. This internal heating is a powerful force, but it’s not the only game in town.

The universe is a busy, often violent place, and dwarf spheroidal galaxies often find themselves caught in the gravitational pull of much bigger galaxies, like our own Milky Way. When a large galaxy tugs on a smaller one, it can rip away its outer layers — a process called tidal stripping. This external stripping accelerates the heating and expansion of the dwarf galaxy, nudging it toward that dynamical attractor even faster. But even dwarf galaxies that are floating alone in the cosmic void, isolated from the gravitational harassment of their larger neighbors, still evolve toward this attractor through their own internal heating. It just takes them a bit longer. For example, a dwarf galaxy in isolation might need as long as 14 billion years — essentially the age of the universe — to fully reach its stable form.

So, how do Peñarrubia and Nadler know this isn't just some clever mathematical conjecture? They didn't just concoct a theory out of thin air. These researchers built entire tiny universes, running elaborate "N-body experiments" — fancy computer simulations that track the motions of zillions of stellar particles and dark subhaloes over billions of years. They even placed some of their model dwarf galaxies on eccentric orbits around a simulated Milky Way, just to see how the relentless tug of tides would affect things. Their experiments showed that a dwarf spheroidal galaxy has to shed more than 99% of its initial dark matter before it starts losing a significant number of its stars, thanks to how the stars and dark matter separate over time.

And they didn't stop there. They also applied what they call the "Heating Argument" to real-world data from the dwarf galaxies orbiting our Milky Way. What they found was fascinating: these galaxies follow specific "tidal tracks" that match what you'd expect from their model. Their stellar orbits, on average, expand to a point where the speed at which the stars are jiggling around — what astronomers call the velocity dispersion — is about half the peak speed that dark matter could make them go within the halo. This holds true for different theoretical dark matter distributions, whether they’re "cuspy" like a sharp peak or "cored" like a gentle plateau. For a common stellar distribution model, the ratio could be 0.54, or for another, 0.48. It’s a remarkable consistency, suggesting a universal behavior.

This all means that the incredible diversity we see in dwarf spheroidal galaxies today — their different sizes and internal motions — isn't necessarily a snapshot of how they were born, like distinct species. Instead, it’s a dynamic story of evolution, a journey driven by both internal gravitational jostling from dark subhaloes and external tidal forces from larger neighbors. They're all marching toward a common, stable state, a kind of cosmic destiny. The structural diversity we observe is largely an evolutionary outcome, not just a random scattering of initial conditions. This reframes our understanding of their very structure and persistence.

Of course, science is never truly settled. We still have many puzzles to crack. Attempts to figure out the exact dark matter distribution inside these galaxies are notoriously tricky, partly because of what's called the "mass-anisotropy degeneracy." It’s difficult to tell if stars are moving in perfectly random directions or if there's a preferred direction, which makes calculating the dark matter's gravitational pull a real headache. Plus, we often can't tell the full 3D orientation of these dim galaxies along our line of sight, adding another layer of uncertainty to their total halo masses and density profiles. So, while we have a brilliant new framework, the precise total masses and density profiles of individual dwarf spheroidal galaxies remain elusive. This model, for instance, simplifies by not fully accounting for how dark subhaloes affect the smooth overall dark matter potential.

Still, this work gives us a powerful new lens through which to view these tiny, dark-matter-dominated worlds. It highlights how the subtle, ongoing interactions within and around a galaxy can completely reshape its destiny. The universe, it seems, has a way of guiding even its smallest inhabitants toward predictable, stable forms, offering a tantalizing glimpse into the grand, unfolding story of cosmic evolution. What other hidden attractors are out there, waiting for us to discover? We've got a lot more to learn about how these cosmic dance partners choreograph their lives, and the detective work continues, one tiny, dark galaxy at a time.

Astronomers have discovered dozens of faint ribbons of stars in the outskirts of the Milky Way using data from the European Space Agency's Gaia mission.

The findings were made using a new algorithm that more than quadruples the number of known candidates of these so-called "stellar streams." This discovery could offer fresh clues about how our galaxy evolved and how its dark matter is distributed, the study's researchers say.

Stellar streams are arcing threads of stars that form when compact star clusters travel through the Milky Way's gravitational field, shedding stars that are stretched out into long, trailing ribbons.

"It's like riding a bike with a bag of sand, only the bag has a hole in it," study co-author Oleg Gnedin, a theoretical astrophysicist at the University of Michigan, said in a statement. "Those grains of sand are like the stars left behind along their trajectory."

Finding stellar streams is valuable because the shapes and motions of these phenomena preserve a record of what gravitational forces have acted on them over time. That makes them powerful tools for mapping the Milky Way's mass, and that mass measurement would include its elusive dark matter halo — dark matter being the invisible "glue" thought to hold galaxies together, but has yet to be observed directly despite decades of effort.

The new study, led by Yingtian "Bill" Chen of the University of Michigan, identifies 87 stellar stream candidates associated with globular clusters, which are dense, ancient groupings of stars that orbit the Milky Way. Previously, fewer than 20 stellar streams had been identified, often only serendipitously in Gaia data, leaving astronomers with too small a sample size to draw broad conclusions.

Most known stellar streams come from dwarf galaxies or clusters that have already been largely torn apart. Streams from still-surviving globular clusters, like those identified in the new study, are much rarer and especially useful because astronomers can compare the stream directly with its parent cluster.

To find them, Chen developed a computer algorithm called StarStream, which searches for streams using a physics-based model rather than relying on visual patterns alone, according to the study. The team then applied the method to Gaia data, which from 2014 to 2025 mapped the positions and motions of billions of stars in the Milky Way.

"It turns out that it's a lot easier to find things when you have a theoretical expectation of what you're looking for when you have a simple phenomenological picture," Gnedin said in the statement.

The results also revealed that many streams do not match the classic expectation of thin, well-aligned trails. Instead, the study reports that some of the newfound streams are shorter, wider or even misaligned with their parent clusters' orbits — suggesting earlier searches may have missed them by focusing only on the most obvious structures.

The expanded sample also provides evidence that some diffuse globular clusters are shedding stars at unusually high rates, a sign they may be nearing complete tidal disruption, the study reports.

Not all 87 candidates are expected to be confirmed, however, as some detections have lower confidence due to background contamination from unrelated stars, the researchers say.

The study's results, along with the algorithm applied to them, can be tested with upcoming observations from next-generation facilities — including the Vera C. Rubin Observatory, NASA's Nancy Grace Roman Space Telescope and the Dark Energy Spectroscopic Instrument — to help verify which streams are real, Chen said in the statement.

"It'll be very easy to adjust the algorithm to future missions," he said. "Once we have the data, it will be very straightforward to apply it."

This research is described in a paper published March 23 in The Astrophysical Journal.

The local universe may be expanding more slowly than previously thought, scientists have found. The discovery, made in two separate pieces of research, could relieve one of the most troubling headaches in cosmology, the Hubble tension.

The Hubble constant — named after Edwin Hubble, the astronomer who found in the early 1900s that the universe is expanding — is the rate at which that expansion is occurring.

The Hubble tension arises from the fact that the observation of the local universe delivers a different value for the Hubble constant than that derived using the cosmic microwave background (CMB) — the universe's first light, which shone shortly after the Big Bang. Astronomers take CMB measurements and then wind forward using the standard model of cosmology, the so-called Lambda cold dark matter (LCDM) model.

The discrepancy has persisted even as the two separate measurement techniques have become more precise. It is troubling because it suggests that some crucial ingredient of physics is missing from our recipe for the cosmos. Hence many astronomers cite the need for a third method to help bridge this disparity, or at least shed some light on why it exists.

Two new studies suggest a new way of measuring expansion in the immediate cosmos by analyzing the motion of two nearby galaxy groups. Galaxies within these groups are simultaneously bound together by mutual gravity and dragged apart by the cosmic flow caused by the stretching of the space in which they are embedded.

Both results indicate that the universe is expanding more slowly in our vicinity than previously estimated. Not only does this technique bring measurements of the Hubble constant in the nearby universe closer in line to those made using the CMB and the LCDM model, but it also suggests that less dark matter is needed to explain cosmic observations and the dynamics of galaxies.

Halo or no?

The teams reached their conclusions by examining two galaxy groups — the Centaurus A group (one of the nearest to us, barring the Milky Way's local group), and the M81 group. Rather than using observations of nearby Type Ia supernovas or the cosmic fossil of the universe's first light represented by the CMB to measure the Hubble constant, the researchers used the motion of these grouped galaxies under the balancing act of the attractive influence of gravity and the repulsive effect of the expansion of the universe.

The astronomers found that the dozens of small galaxies that comprise the Centaurus A group are not in fact dominated by the giant elliptical galaxy of the same name. Rather, this galaxy actually forms a binary with the group's M83 galaxy.

The M81 group was already understood to have binary galaxies (M81 and M82) at its heart. The new research revealed that, though the structure of this group is neatly organized, the inner region of around 1 million light-years is tilted by about 34 degrees with regard to its wider surroundings. Out to a distance of around 10 million light-years, the orientation of the M81 group aligns with that of a vast sheet-like structure of matter that reaches out to the Centaurus A group.

The two teams of scientists also discovered that, in addition to the two galaxy groups sharing a similar environment, the masses of the brightest galaxies in these groupings account for most of the total mass. Thus, the motions of all the galaxies within the groupings can be considered a result of the interplay of the gravitational influence of these bright galaxies and the cosmic flow of the expanding universe.

This means that, in contradiction to the predictions of cosmic simulations, galaxy groups don't have to be embedded in a vast, all-encompassing dark matter halo exerting its gravitational influence.

What does this mean for the Hubble constant?

The Hubble constant is measured in kilometers per second per megaparsec (km/s/Mpc), with 1 megaparsec being equivalent to around 3.3 million light-years. Currently, when researchers calculate the expansion rate of the universe using local Type Ia supernovas, they obtain a Hubble constant of 73 km/s/Mpc. When the Hubble constant is calculated using the CMB, however, theorists calculate a lower value of 68 km/s/Mpc.

The teams involved in this research arrived at a Hubble constant value of 64 km/s/Mpc. This implied to the researchers that part of the Hubble tension is caused by the methods scientists use to measure the Hubble constant. This could mean that an added, currently unknown element of the cosmos isn't needed to dispel the Hubble tension; we can complete this cosmic recipe with the ingredients we have at hand.

Of course, there is still a long way to go before this method overturns existing paradigms. With the technique applied to just two local galaxy groups, the Hubble tension is bound to be a headache for at least a little while longer.

The next step for this investigation will be to apply this galaxy-group study technique to a wider region of space within our local universe. This could become possible when observations of galaxy groups at larger distances become available in the next data release from the 4-meter Multi-Object Spectroscopic Telescope (4MOST).

The team's research was published across two papers in the journal Astronomy & Astrophysics.

All galaxies are dominated by dark matter, an invisible "stuff" that outweighs all of the matter comprising stars, planets, and moons by around five to one. But in some galaxies, dark matter takes this domination to the extreme. Using the Hubble Space Telescope along with the Euclid Space Telescope, astronomers have discovered what seems to be one of the most heavily dark-matter-dominated galaxies ever seen.

This "dark galaxy," officially designated CDG-2, is located around 245 million light-years away. Unlike regular galaxies, which are bright and prominent even across vast cosmic distances, dark galaxies like CDG-2 are faint, nearly invisible and ghost-like thanks to a sparse smattering of stars and their huge quantity of dark matter.

The team behind the discovery of this galaxy found that, unlike standard galaxies, in which dark matter outweighs ordinary matter by a ratio of five to one, dark matter accounts for a staggering 99% of the mass of CDG-2.

Dark matter is effectively invisible, because unlike protons, neutrons, and electrons  — the particles that comprise everyday matter  — whatever composes dark matter doesn't interact with electromagnetic radiation, that's "light" to you and me. Scientists have been able to determine that galaxies are ruled by dark matter, with dense central cores and halos that extend far beyond visible gas and dust, due to the fact that dark matter does interact with gravity.

This gravitational influence then influences visible matter and light, a knock-on effect which astronomers can see. Even so, dark galaxies are extremely tough to detect.

The discovery of CDG-2 began when a team of astronomers investigated tight groupings of stars called globular clusters, which can often indicate the presence of a hidden population of dim stars in their vicinity. This led to the confirmation of ten faint low-brightness galaxies and two dark galaxy candidates.

To confirm the existence of one of these dark galaxies, the researchers turned to Hubble, Euclid, and the Subaru Telescope in Hawaii.

Hubble data confirmed a tight grouping of four globular clusters in the Perseus galaxy cluster, located around 300 million light-years away. Further observations from Hubble, along with data from Euclid and Subaru, revealed a faint glow around these globular clusters, which served as evidence of a hidden, near-invisible galaxy lurking behind these globular clusters. CDG-2 had revealed itself.

"This is the first galaxy detected solely through its globular cluster population," team leader David Li of the University of Toronto, Canada, said in a statement. "Under conservative assumptions, the four clusters represent the entire globular cluster population of CDG-2."

Li and colleagues performed a deeper analysis of CDG-2, finding that it has a brightness equivalent to that of around 6 million sun-like stars. They determined that around 16% of this brightness was accounted for by the overlying globular clusters. The normal matter in this dark galaxy is thought to have enabled star formation in its past, but the team theorizes these stellar bodies have been stripped away by gravitational interactions with other galaxies. The globular clusters used to detect CDG-2 were able to withstand this gravitational interference due to how densely packed with stars they are, leaving them the only tracers of a now ghostly galaxy.

The team's results were published in The Astrophysical Journal Letters.

The universe is a vast, unseen loom, weaving galaxies into an intricate cosmic web through invisible threads of matter. This cosmic web is the fundamental scaffolding of everything we see, dictating where galaxies form and how they evolve. Much of this architecture remains a mystery, its delicate pathways hidden, and uncovering these cosmic threads requires new eyes and persistent effort.

But a new observation has helped us trace one in the Ursa Major Supergroup. In a preprint paper published on the open source repository arXiv, a team of scientists pinpointed a group of galaxies that stretch out in a line spanning nearly four light-years, a discovery that unveils a delicate, thin filament – a hidden pathway, dominated by dark matter, where galaxies are born and evolve in synchronized dances.

It's a glimpse into the universe's secret architecture, revealing how even the most subtle cosmic structures orchestrate the grand ballet of creation, guiding the destiny of galaxies across the eons. We are learning how the universe truly puts itself together, one subtle thread at a time.

Astronomers have long understood that the universe isn't a uniform soup of stars and gas. It's organized into a gigantic, intricate network, much like a spider's web. This is the cosmic web, a structure with dense knots of galaxies, long strands connecting them, and vast, empty spaces. Gravity, acting over billions of years, pulls matter together to form this architecture. Much of this matter is something we cannot directly observe: dark matter.

Imagine huge amounts of invisible stuff in space. We can't see it because it doesn't interact with light. But its gravity pulls on everything we can see, making objects move in ways they wouldn't otherwise. It's a hidden gravitational scaffolding that shapes the universe. These long strands, filaments of the cosmic web, are dominated by this unseen dark matter. They act as cosmic highways, guiding gas flow that feeds new generations of stars and galaxies.

Powerful new instruments are uncovering the universe's secrets. China's FAST telescope, the Five-hundred-meter Aperture Spherical radio Telescope, did just that recently when its incredible sensitivity allowed astronomers to peer into previously faint or diffuse regions. Using FAST HI observations, a team identified a group of galaxies with a nearly linear distribution extending from northeast to southwest. This finding represents a coherent structure: galaxies lined up in space. It's like finding a single, almost invisible thread woven into a giant, dusty tapestry.

This discovery reveals a delicate thin filament, a previously unnoticed cosmic pathway. Identifying this distinct, linear arrangement provides direct observational evidence for these predicted, yet often hard-to-spot, components of the cosmic web. This shows the power of new instruments, observing what was once theoretical. These linear groupings offer tangible proof of the cosmic web's intricate design, especially its more subtle strands.

A line of galaxies, a cosmic filament, carries significant implications for understanding the universe's architecture. These linear arrangements are not random. They hint at the unseen cosmic web, showcasing how dark matter guides galaxy formation. Dark matter's gravitational pull within these filaments acts like a cosmic funnel, drawing in gas and dust, providing raw materials for new stars and galaxies.

This observation shows how subtle cosmic architecture directs galaxies' destinies, influencing their formation, interactions, and evolution. Just like living organisms, galaxies aren't static; they are born, grow, change their appearance, and sometimes even merge with other galaxies over billions of years.

This newly identified filament serves as a prime example of a cosmic nursery, where dark matter's gravitational pull creates conditions for galaxies to coalesce and begin their journey. It implies even these faint structures play a crucial role in cosmic development. We are only just beginning to grasp their full extent and long-term role in galaxy evolution.

New research suggests the supermassive black hole at the heart of the Milky Way is actually a tremendously massive yet compact clump of dark matter.

Scientists say this clump would exert the same gravitational effects currently attributed to the Milky Way's supermassive black hole, Sagittarius A* (Sgr A*). That includes the violent and rapid dance of stars taking place at the Galactic Center, in which so-called "S-stars" race around the compact heart of our galaxy at speeds as great as 67 million miles per hour (30,000 kilometers per second). For context, that's around 10% of the speed of light. This dark matter clump, the team says, would also account for the orbits of the dust-shrouded bodies, or "G-sources" located in the Galactic Center.

However, this substitution of a black hole for dark matter only works if dark matter is composed of ultra-light particles that are part of the "fermion" family. This would grant the dense cluster at the heart of the galaxy the ability to form a cosmic structure that matches those observed characteristics of the Galactic Center.

Fermionic dark matter is proposed to be capable of forming a structure that consists of a super-dense, compact core with so much mass that it mimics a supermassive black hole with a mass equivalent to 4.6 million suns, the research team says. That core would be surrounded by a vast and diffuse halo stretching out far beyond the visible matter of the Milky Way — but acting as a single unified entity. This is a structure that other recipes of dark matter can't replicate.

"We are not just replacing the black hole with a dark object; we are proposing that the supermassive central object and the galaxy's dark matter halo are two manifestations of the same, continuous substance," team member Carlos Argüelles, of the Institute of Astrophysics La Plata, said in a statement.

Seeing is believing … but what are we seeing?

The theory, proposed by Argüelles and colleagues, is strongly based on observations conducted by the European Space Agency's star tracking mission Gaia, released as part of the project's third data drop in June 2022.

Gaia allowed the team to precisely map the rotation and orbit of stars and gas in the outer halo of the Milky Way, revealing a slowdown of our galaxy's rotation curve: the so-called Keplerian decline. This team thinks the Keplerian decline can be explained by the diffuse outer halo they saw, which is a factor in their model and one that, as we now know, adds support to the fermionic model of dark matter.

In the standard model of cosmology, also known as the Lambda Cold Dark Matter (LCDM) model (the best description we have of the universe), dark matter is "cold," which means its particles move at speeds significantly slower than the speed of light.

Cold dark matter forms an extended halo tail that struggles to account for the slowdown observed by Gaia. The fermionic model, on the other hand, predicts a tighter and more compact halo tail that could cause Keplerian decline. Remember, in the Sgr A* model, dark matter at the heart of the Milky Way isn't connected in a single structure to the outer halo, thus that tail isn't present in this model.

"This is the first time a dark matter model has successfully bridged these vastly different scales and various object orbits, including modern rotation curve and central stars data," Argüelles said.

So far, so good. The theory that our galaxy may have a clump of dark matter rather than a black hole in its center appears to be fairly credible. However, there is a 4.6 million solar mass elephant in the room: namely, the image of Sgr A* captured by the Event Horizon Telescope (EHT) and revealed to the public in May 2022. Still, the team says their fermion dark matter model can account for this.

Before diving into that explanation, it is worth considering what we actually see when we look at the EHT image of what we all currently assume to be Sgr A*.

The glowing golden ring in this image is actually superhot matter whipping around whatever lurks at the heart of the Milky Way. What we actually see in this image isn't a black hole at all, understandable because black holes are surrounded by a light-trapping surface called an event horizon; there's no way we could directly see Sgr A*. What we can see, though, is the shadow the black hole casts.

Yet in 2024, researchers demonstrated that a dense core of fermionic dark matter could actually cast a shadow that is similar to that seen in the EHT image. The core would be invisible like a black hole because dark matter famously doesn't interact with light.

"This is a pivotal point," said team leader Valentina Crespi of the Institute of Astrophysics La Plata. "Our model not only explains the orbits of stars and the galaxy's rotation but is also consistent with the famous 'black hole shadow' image. The dense dark matter core can mimic the shadow because it bends light so strongly, creating a central darkness surrounded by a bright ring."

Though the team has statistically compared their dark matter model to the accepted model of a supermassive black hole at the heart of the Milky Way, and the former was able to replicate the behavior of S-stars, G-sources, the structure of our galaxy and the black hole shadow, the researchers emphasize it is definitely still early days for this theory.

The team's research does lay down a roadmap for future observations using the Very Large Telescope (VLT) to hunt for photon rings at the heart of the Milky Way, which will be present for Sgr A*, but absent if the central dominating body of our galaxy is a dense clump of dark matter.

Clearly, Sgr A* isn't ready to relinquish its throne at the heart of the Milky Way to dark matter just yet.

The team's research was published on Feb. 5 in the journal Monthly Notices of the Royal Astronomical Society (MNRAS).

New research suggests that dark matter, the universe's most puzzling and mysterious substance, may not exist. But removing dark matter from our cosmological models could hinge on the possibility that gravity behaves differently on very large scales, one scientist says.

Dark matter has been a thorn in the side of physicists because, despite outweighing ordinary matter by a ratio of 5 to 1, it remains effectively invisible. That's because it doesn't interact with light, or more technically, electromagnetic radiation. Because the particles that comprise the atoms that make up stars, planets, moons, living things, and everything we see around us, do interact with light, scientists have been searching for particles that could make up dark matter. However, this addition to particle physics, which has thus far eluded all attempts to uncover it, isn't needed if we are wrong about how gravity behaves on galactic scales. At least, that is what Naman Kumar of the Indian Institute of Technology suggests.

"The mystery of dark matter — unseen, pervasive, and essential in standard cosmology — has loomed over physics for decades," Kumar wrote for Phys.org. "In new research, I explore a different possibility: Rather than postulating new particles, I propose that perhaps gravity itself behaves differently on the largest scales."

The only reason that scientists have inferred the presence of dark matter is that this strange matter does interact with gravity. In fact, the first hint of dark matter came from the fact that galaxies were observed to be spinning so rapidly that if the gravity of their visible matter was the only force acting to keep them together, they would have flown apart long ago.

Another line of evidence comes from a phenomenon called "gravitational lensing," which occurs when the usually straight path of light is curved by a dent in the fabric of space generated by objects of great mass. This deflection has been found to be too extreme to be accounted for by the visible matter in lensing galaxies. Hence, physicists have inferred that galaxies are embedded with vast haloes of dark matter that extend far beyond their haloes of stars.

The fact that the only evidence for dark matter comes from its gravitational effect on space and by extension everyday or "baryonic" matter explains why a modified theory of gravity could do away with the need for dark matter to exist.

Don't be a square

To investigate this, Kumar looked at gravity through the lens of quantum field theory and at very small scales equivalent to the wavelength of infrared light, a so-called "infrared running scheme." This involved not assuming that Newton's gravitational constant, or "Big G," is allowed to change or "run" at different length scales.

"What emerged is a compelling theoretical case for a scenario in which gravity's effective strength subtly shifts over galactic distances," Kumar wrote.

Gravity is just one example in physics of an "inverse square law" of 1/r^2, meaning that its strength falls off by the square of the distance from a source; when the distance from a gravitating body doubles, then its gravity becomes four times weaker. If the distance is tripled, then the gravitational influence becomes nine times weaker.

Considering his infrared running scheme, Kumar found a gravitational potential that deviates from the usual inverse force law, leading to a long-range force of 1/r. This can lead to the type of rotation seen for galaxies that is currently attributed to dark matter halos.

"These results suggest that the infrared running scenario could account for galaxy rotation without invoking a dominant cold dark matter component," Kumar explained.

As you might expect, because dark matter is considered to account for 85% of the matter in the universe, it stands to reason that removing it from our models of the cosmos has significant implications for understanding how the universe evolved and continues to evolve. However, Kumar's model may fit well with current expectations and observations.

"In the early universe — at the time of the cosmic microwave background and during structure formation — any change in gravity must be small enough to avoid conflict with precision cosmological measurements," Kumar wrote. "Within the infrared running framework, corrections grow slowly with scale and time, preserving agreement with early-universe constraints while becoming relevant only at later epochs and large scales."

The next step for Kumar's theory of infrared-running gravity will be to see how it compares to measurements of gravitational lensing and the gathering of galaxy clusters, currently thought to occur around a framework of dark matter.

"My work opens a path toward understanding dark matter phenomena not as missing particles, but as a subtle feature of gravitation itself — a deep consequence of scale dependence in a quantum field theory of gravity," Kumar concluded. "Although this approach does not yet fully replace dark matter in the cosmological standard model — especially in explaining detailed structure formation and lensing data — it highlights gravity's possible hidden complexity and invites a reevaluation of where dark matter effects originate."

Kumar's research was published in the journal Physical Review Letters B.

Using the James Webb Space Telescope, astronomers have built a detailed map of dark matter, showing the density of this mysterious stuff across a field of view that encompasses around 800,000 galaxies.

Dark matter is so puzzling to scientists because it doesn't interact with electromagnetic radiation, or simply light,, and is thus effectively invisible to us. This tells researchers that dark matter isn't just difficult-to-see ordinary matter made up of protons, neutrons and electrons, which are particles that do interact with light. Hence, the search for particles that could comprise dark matter has been a complicated one. To make matters even more complex, these particles appear to outweigh particles that comprise ordinary matter in the cosmos by a ratio of five to one.

Fortunately, dark matter does interact with gravity, therefore influencing the very fabric of space and time. And the curvature of space caused by large concentrations of dark matter — like dark matter haloes that envelope galaxies and galactic clusters — can influence the passage of light in a process called gravitational lensing first predicted by Albert Einstein back in 1915. It is through its gravitational influence that astronomers were able to use the James Webb Space Telescope (JWST) to build this new map of dark matter.

The area of the sky analyzed with this investigation is around 2.5 times the size of the full moon (as seen from our vantage point on Earth) and located in the constellation of Sextans. The JWST studied this region for around 255 hours with its Near-Infrared Camera (NIRCam) instrument as part of the Cosmic Evolution Survey (COSMOS).

COSMOS is conducted by around 15 different telescopes, including the JWST's trusty sibling the Hubble Space Telescope. These eyes on the universe all repeatedly study a larger section of the sky equivalent to around 10 full moons. This repetition with instruments that see the cosmos in different ways allows scientists to investigate how galaxies grow, with Hubble and JWST data helping to unravel the role dark matter plays in things like galactic evolution.Additionally, Hubble observed the same region involved in the new study back in 2007, and the section has since been investigated by many other ground-based telescopes independently. But the immense sensitivity of the JWST has helped scientists produce a map with around 10 times more galaxies than those produced by ground telescopes and twice as many as seen in the Hubble map.

Using these JWST observations, the team inferred the distribution of dark matter using "weak gravitational lensing" in particular, which is the subtle distortion of light from thousands of background galaxies caused as it passes warped space caused by concentrations of dark matter.

Additionally, observing the region with the JWST's other main instrument, Mid-Infrared Instrument (MIRI), allowed the researchers to better measure the distances to the galaxies in this section of the sky.

The new dark matter map is just another example of how the JWST is revolutionizing our view of space, both near and far, while redefining our understanding of familiar bodies as well as the most mysterious aspects of the cosmos.

An incredibly energetic "impossible" particle that hit Earth in 2023 may have been debris from an exploding primordial black hole formed during the Big Bang. If that is the case, then it could prove the existence of primordial black holes, which could then help explain what the universe's most mysterious "stuff," dark matter, is made of.

The particle in question was a neutrino with an energy 100,000 times greater than that of the highest-energy particles produced by the world's largest and most powerful particle accelerator, the Large Hadron Collider (LHC). In fact, the particle was so energetic that scientists aren't aware of any natural cosmic phenomena powerful enough to create it.

Now, a team of researchers from the University of Massachusetts Amherst suggests that a particle like this could be blasted out when a so-called "quasi-extremal primordial black hole" explodes.

The key to black hole explosions is the leaking of Hawking radiation, a type of thermal radiation named for physicist Stephen Hawking, who first proposed its existence in 1974. The hotter a black hole is, the quicker it leaks Hawking radiation, losing mass and then finally ending its life in a massive explosion.

The catch is that the bigger a black hole is, the colder it is, and the more slowly it loses thermal radiation to its surroundings. Thus, even the smallest stellar mass black holes, born when massive stars go supernova at the end of their lives, would take about 10^67 years, vastly longer than the age of the universe, to leak enough radiation to reach this explosive stage.

However, Hawking also theorized that another type of black hole may exist, one born not from the death of a star but directly from density fluctuations in the "primordial sea" of ultrahot particles that filled the cosmos during its first moments after the Big Bang. And because these primordial black holes can be extremely small, with masses down to that of a planet or even a large asteroid rather than 3 to 5 times the mass of the sun, like the smallest stellar mass black holes, then they could be hot enough to leak Hawking radiation efficiently enough to explode.

"The lighter a black hole is, the hotter it should be and the more particles it will emit," team member Andrea Thamm of the University of Massachusetts Amherst said in a statement. "As primordial black holes evaporate, they become ever lighter, and so hotter, emitting even more radiation in a runaway process until explosion. It's that Hawking radiation that our telescopes can detect."

The astronomers behind this research estimate that a primordial black hole should explode with a frequency of around one every ten years or so. Thus far, none of these explosions have been detected, and therefore, primordial black holes and Hawking radiation both remain purely theoretical. That is, of course, unless evidence of an exploding primordial black hole was discovered courtesy of a different type of detection, the true nature of which wasn't immediately grasped.

The impossible particle

The impossibly energetic neutrino was detected in 2023 by a network of neutrino detectors called KM3NeT located in the Mediterranean Sea.

"Observing the high-energy neutrino was an incredible event," team member and University of Massachusetts Amherst researcher Michael Baker said. "It gave us a new window on the universe. But we could now be on the cusp of experimentally verifying Hawking radiation, obtaining evidence for both primordial black holes and new particles beyond the Standard Model, and explaining the mystery of dark matter."

However, there is a hitch. The event wasn't picked up by a similar neutrino detector called IceCube, situated deep within the ice of the South Pole. That was a problem, because IceCube was specifically designed to detect high-energy neutrinos, and yet it's never detected one of these particles with even 1/100 of the energy of the impossible neutrino.

If a primordial black hole explodes once a decade, then IceCube should be bombarded with high-energy neutrinos. So where are they?

The University of Massachusetts Amherst team has a theory.

"We think that primordial black holes with a 'dark charge' — what we call quasi-extremal primordial black holes — are the missing link," team member Joaquim Iguaz Juan of the University of Massachusetts Amherst said.

A "dark charge" is a version of the electromagnetic force that we are familiar with, but is carried not by a standard electron, but by a much heavier relative, a hypothetical particle called a "dark electron."

"There are other, simpler models of primordial black holes out there," Baker said. "Our dark-charge model is more complex, which means it may provide a more accurate model of reality. What's so cool is to see that our model can explain this otherwise unexplainable phenomenon."

A primordial black hole with a dark charge would have unique properties that make it behave differently from a standard primordial black hole, and that could not only explain the impossible neutrino but it could also solve the mystery of what dark matter actually is.

Dark matter has been so problematic because, unlike the particles that comprise standard matter, it doesn't interact with electromagnetic radiation, or "light." This means that despite outweighing ordinary particles by a ratio of 5 to 1, dark matter is effectively invisible and totally mysterious. One possible candidate for dark matter is primordial black holes.

"If our hypothesized dark charge is true, then we believe there could be a significant population of primordial black holes, which would be consistent with other astrophysical observations, and account for all the missing dark matter in the universe," Iguaz Juan concluded.

The team's research was accepted for publication in the journal Physical Review Letters.

Scientists have been gifted with a clearer picture of the expansion of the universe and dark energy, the mysterious force driving the acceleration of this expansion, than ever before. This comes courtesy of the analysis of six years' worth of data collected by the Dark Energy Camera (DECam) mounted on the U.S. National Science Foundation Víctor M. Blanco 4-meter telescope.

The data analysed consists of 758 nights of observations of one-eighth of the sky conducted by the Dark Energy Survey (DES) Collaboration between 2013 and 2019, during the deep, wide-area survey of the sky conducted using the 570-megapixel DECam, which recorded information from 669 million galaxies located billions of light-years from Earth.

This analysis represents the first time the four separate methods of studying dark energy have been united as one. The results doubled the strength of the constraints on the effect of dark energy, an essential step toward discovering the true nature of this mysterious force that dominates the universe.

"These results from DES shine new light on our understanding of the universe and its expansion," Regina Rameika, Associate Director for the Office of High Energy Physics in the Department of Energy’s Office of Science, said in a statement. "They demonstrate how long-term investment in research and combining multiple types of analysis can provide insight into some of the universe’s biggest mysteries."

An expanding problem

The first hints of dark energy were uncovered in 1998 when two separate teams of astronomers observed distant supernovas, finding that the further away they were, the faster they were receding away from Earth. That not only confirmed that the universe is expanding as Edwin Hubble suggested a century ago, but shockingly revealed that this expansion is accelerating. Dark energy is the placeholder name given to whatever is driving this acceleration. In the 28 years since that discovery, scientists have determined that dark energy accounts for around 68% of the total energy and matter budget of the cosmos. It has also been discovered that dark energy hasn't always dominated the 13.8 billion-year-old universe in this way; its effect only "kicked in" and overwhelmed the attractive force of gravity at large scales between 3 and 7 billion years ago. These findings have only emphasised the need to understand what dark energy is.

This new analysis considered Type-Ia supernovas, the same type used to first discover dark energy, in addition to three other probes of cosmic structure and expansion. Those other phenomena are so-called weak gravitational lensing, a phenomenon that occurs when light from a background source passes an object of great mass and is curved; the clustering of galaxies; and so-called baryon acoustic oscillations, fluctuations of density in the early universe caused by pressure waves frozen into space around 380,000 years after the Big Bang. "It is an incredible feeling to see these results based on all the data, and with all four probes that DES had planned," DES Collaboration member Yuanyuan Zhang, of NOIRLab, said. "This was something I would have only dared to dream about when DES started collecting data, and now the dream has come true."

Using the data provided by DECam and the techniques described above, the DES team reconstructed matter distribution over the past 6 billion years of cosmic history. They then compared these results against two of the prevailing models of the universe. These are the standard model of cosmology, also known as the Lambda Cold Dark Matter (LCDM) model, in which dark energy is stable over time; and the extended model (wCDM), in which dark energy is allowed to evolve over time.

The DES results conformed well to the LCDM, but also fit nicely with the wCDM.

But there is one parameter that these new results found to be off in comparison to both of these cosmic models: how matter in the modern universe is predicted to cluster based upon measurements of the early universe. These findings not only confirmed that modern galaxies don't cluster as either the LCDM or the wCDM predicts, but the difference between observations and theory became even more pronounced.

The next step for DES will be to combine DECam data with observations of around 20 billion galaxies from the recently completed Vera C. Rubin Observatory when it begins its decade-long Legacy Survey of Space and Time (LSST).

This should present an even clearer picture of the history of the universe and the nature of dark energy.

"DES has been transformative, and the Vera C. Rubin Observatory will take us even further," Chris Davis, National Science Foundation Program Director, said. "Rubin's unprecedented survey of the southern sky will enable new tests of gravity and shed light on dark energy."

The team's research has been submitted to the journal Physical Review D and is available on the paper repository site arXiv.

New research suggests that dark matter, the universe's most mysterious "stuff," may actually have been born "hot." If this is the case, the best current model we have of cosmic evolution, the standard model of cosmology, also known as the Lambda Cold Dark Matter (LCDM), may need serious revision or overwriting altogether, altering the rules of the epic game of hide and seek that has been ongoing between dark matter and scientists for decades.

Dark matter is a headache for researchers because it doesn't interact with electromagnetic radiation, light, in layman's terms. This not only makes dark matter effectively invisible, but it also means that scientists know it can't be made of the electrons, protons, and neutrons that compose the atoms making up everything from the most massive stars down to the tiniest bacteria, because they do interact with light. Couple this with the fact that dark matter outweighs ordinary matter in the universe by a ratio of five to one.

This mystery has sparked a search for candidate particles for dark matter beyond the standard model of particle physics. Thus far, this search has favored "cold" dark matter, which doesn't refer to temperature but instead references the speed at which the particles move (cold meaning much slower than light, hot meaning moving at speeds approaching light). In the standard picture, cold dark matter emerges from the hot and dense soup of energy that filled the early universe.

The new research suggests an alternative origin. Dark matter could have instead been born extremely hot, opening up alternative possibilities of how it interacts with everyday matter.

The team proposes that incredibly hot dark matter moving at near-light speeds could have been born in the universe during a period called post-inflationary reheating. This refers to the point at which the inflation field driving the rapid initial expansion of the universe decayed and transformed into a hot and incredibly dense "soup" of radiation and particles.

"Dark matter is famously enigmatic. One of the few things we know about it is that it needs to be cold," research leader Stephen Henrich, of the University of Minnesota's School of Physics and Astronomy, said in a statement. "As a result, for the past four decades, most researchers have believed that dark matter must be cold when it is born in the primordial universe.

"Our recent results show that this is not the case; in fact, dark matter can be red hot when it is born but still have time to cool down before galaxies begin to form."

Henrich and his colleagues demonstrated that dark matter could stop significantly interacting with ordinary matter and electromagnetic radiation while still very hot and thus moving at speeds approaching that of light, a process called "decoupling." If produced during post-inflationary reheating, this would give dark matter plenty of time to cool off and start acting like cold dark matter, assisting in the formation of the first galaxies by forming gravitational waves into which ordinary matter clusters.

The concept could resurrect one of the earliest and simplest candidates for dark matter, low-mass neutrinos, which were ruled out around four decades ago because it was thought they would have wiped out galactic-scale structures rather than promoting them.

"The neutrino became the prime example of hot dark matter, where structure formation relies on cold dark matter," team member Keith Olive, also of the University of Minnesota's School of Physics and Astronomy, said. "It is amazing that a similar candidate, if produced just as the hot Big Bang universe was being created, could have cooled to the point where it would, in fact, act as cold dark matter."

The team will now attempt to produce and observe these particles using experiments on Earth, including tests conducted with powerful particle accelerators, as well as detecting them in the early universe. This investigation could not only reveal the true nature of dark matter, but it could also help scientists build a clearer picture of one of the most crucial, yet mysterious, periods of cosmic evolution.

"With our new findings, we may be able to access a period in the history of the universe very close to the Big Bang," team member Yann Mambrini of the Université Paris-Saclay in France said.

The team's research was published in November in Physical Review Letters.

In 1971, astronaut David Scott stood on the lunar surface, holding a hammer and a feather, and in the vacuum of the moon, he let them go. They struck the gray dust at the exact same time. It was a poetic nod to Galileo, who, centuries earlier, disproved the Aristotelian notion that heavy objects "want" to be on the ground more than light ones do.

This wasn't just a parlor trick for the cameras; it was a demonstration of the weak equivalence principle, which is the bedrock of general relativity. It states that all objects, regardless of their mass or internal composition, fall at the exact same rate in a gravitational field. When Einstein was building his masterpiece theory, he didn't try to explain why this happens. He simply assumed it was a fundamental rule and moved on.

But what if there's an astrophysical creature that refuses to play by the rules? What if we dropped something so exotic, it wasn't even on Einstein's radar? We need to talk about antimatter.

To understand the allure of falling antimatter, we have to look at the history of its discovery. In the 1920s, physicist Paul Dirac was trying to force two very different worlds — quantum mechanics (the rules of the very small) and special relativity (the rules of the very fast) — to play together.

Dirac found an equation that worked, but it had a quirk. Just as the square root of 4 can be both 2 and -2, his equation offered two solutions for the energy of a particle: one positive and one negative. This was a problem. Positive energy has a "ground floor" at zero, but negative energy is a basement of a basement with no bottom.

Dirac's solution was what became known as the "Dirac sea." He imagined outer space not as an empty vacuum but as a filled "ocean" of negative energy states. If you kick one of these invisible particles into the positive realm, you leave behind a hole. That hole behaves like a normal particle but with an opposite charge. It was the first time a particle was predicted by pure math before being seen in a lab. We call it antimatter.

Why focus on antimatter to test gravity? Because antimatter is the bridge to the greatest divide in physics. General relativity (gravity) and quantum mechanics (everything else) famously do not get along. They speak different languages and live in different neighborhoods. Because antimatter is a pure product of the quantum world, it is the perfect candidate to test Einstein's theory of gravity.

However, this is a nightmare, for three reasons:

1. When matter and antimatter touch, they annihilate in a flash of pure energy.
2. Nature doesn't just hand us antimatter; we have to build it in advanced laboratories.
3. Compared with the electromagnetic force, gravity is incredibly weak.

To overcome these hurdles, scientists at CERN's ALPHA-g experiment had to get creative. First, they made neutral antihydrogen by pairing antiprotons with positrons (anti-electrons). Because these antiatoms are neutral, they aren't pushed around by electricity.

The team caught about a hundred of these antiatoms in a Penning trap, which is a magnetic bottle that holds them in place because, while neutral, they still act like tiny bar magnets. Then, using lasers, the researchers chilled the atoms to near absolute zero to stop them from jiggling.

Then came the moment of truth: They slowly turned down the magnetic field.

If antimatter ignored the weak equivalence principle, the atoms might have drifted upward, repelled by Earth. If Einstein was right, they should tumble downward. The researchers waited for the flash of annihilation as the antiatoms escaped the trap and hit the walls of the container. After they filtered out the noise of stray cosmic rays, the results were clear: Roughly 80% of the antiatoms fell through the bottom of the trap.

Antimatter falls down. It's an anti-climactic (ha ha) result in the best way possible. It means the weak equivalence principle holds firm and Einstein's vision of a universal gravitational response remains unblemished.

However, the case isn't entirely closed. While we know antimatter falls down, we don't yet know if it falls at the exact same acceleration as regular matter does. If there is even a 1% difference in the speed of the fall, it would signal a total revolution in physics — a sign that gravity treats mirror matter differently. But for now, the universe remains a place where hammers, feathers and antihydrogen all race to the floor at the same speed.

"Dark stars" could help solve three seemingly disconnected mysteries that emerged at cosmic dawn — mysteries recently discovered by the James Webb Space Telescope. The puzzles include the surprising overabundance of supermassive black holes in the early universe, the unexpected existence of "blue monster" galaxies, and the so-called "little red dots" scientists have been finding. The latter is an entirely new class of cosmic objects in the early universe that appear to have disappeared before the cosmos was around 2 billion years old.

Dark stars are hypothetical objects that are proposed to have existed in the early universe. Rather than being powered by nuclear fusion, as normal stars are, dark stars are thought to have been powered by the annihilation of dark matter particles. "Dark" refers to that source of these stars' energy; they would have, in fact, been incredibly bright.

"Some of the most significant mysteries posed by the [James Webb Space Telescope's] cosmic dawn data are in fact features of the dark star theory," research leader Cosmin Ilie of Colgate University said in a statement.

If dark stars existed, they would have been capable of forming in the universe before ordinary stars could have formed. When ultradense cores of dark matter are exhausted, it is theorized that dark stars could collapse to form the massive "seeds" for supermassive black holes.

These seeds would be much more massive than the black holes formed when even the most massive stars run out of fuel for nuclear fusion. This, coupled with the fact that dark stars could have existed before normal stars, would allow supermassive black holes to form much faster than the standard chain of black hole mergers thought to create supermassive black holes.

That could explain how the JWST has been able to detect a large population of supermassive black holes in the universe less than 1 billion years after the Big Bang.

Those black holes aren't the only unexpected things the JWST has been detecting in the early universe since it began observations in 2022. The $10 billion space telescope has also been spotting extremely bright, ultra-compact and incredibly dense galaxies that lack an abundance of dust. Categorized as "blue monsters," these are galaxies that no cosmological simulation or model of the formation of the earliest galaxies had predicted the existence of prior to the era of the JWST.

The team suggests these blue monsters aren't galaxies at all, but are instead incredibly luminous dark stars that, because of their brightness, are being mistaken for entire galaxies with populations of stars packed into a region no wider than a few hundred light-years.

Little red dots, though much dimmer than blue monsters, are also notable for how compact they are, requiring an almost impossibly dense packing of stars, if they are indeed galaxies. The other puzzling characteristic of little red dots is they emit weakly in ultraviolet light and don't seem to emit X-rays at all.

This team argues the collapse of dark stars that have exhausted their dark matter could result in black holes that are still surrounded by layers of stellar material and that could have the effect of semi-obscuring ultraviolet light and completely obscuring X-ray emissions in a way that the dust haloes of galaxies alone cannot.

For now, dark stars remain purely hypothetical, though some observational evidence is beginning to emerge. Nevertheless, this research represents an intriguing attempt to solve three cosmological puzzles with one mechanism.

"Supermassive dark stars can offer a solution to several pressing puzzles in astronomy and astrophysics, as discussed in depth in this paper," the authors concluded. "To our knowledge, there is no other mechanism that can achieve this simultaneously."

The results are in a paper published in December 2025 in the journal Astrophysics and Cosmology at High Z.

A completely dark and mysterious body with the mass of 1 million suns and a possible black hole heart continues to baffle and intrigue astronomers despite further investigation.

This "mysterious disruptor" is located around 11 billion light-years away and was discovered in 2025 thanks to its gravitational influence. It is now the most distant body ever detected due to its gravitational effects alone.

But astronomers aren't completely in the dark about the mysterious disruptor, however. In fact, they are sure they know what lies at the heart of this strange cosmic body. "The inner central part is consistent with a black hole or dense stellar core, which surprisingly makes up about a quarter of the object's total mass," Vegetti explained. "As we move away from the center, however, the object's density flattens into a large disk-like component. This is a structure we've never seen before, so it could be a new class of dark object."

This strange structure was found in the gravitational lens system JVAS B1938+666. Gravitational lensing is a phenomenon first predicted by Einstein in the 1915 theory of gravity known as general relativity. It occurs when light from a background source passes the curvature of space caused by a massive foreground object, known as a gravitational lens, causing its usually straight path to become curved. The way light is influenced doesn't just allow objects to be seen at great distances via light amplification, but also tells scientists a great deal about the way mass is distributed within the lensing system itself.

The gravitational lens JVAS B1938+666 consists of massive bodies ranging from 6.5 billion to 11 billion light-years away, including this "mysterious disruptor," the most distant element of Jvas B1938+666. A team of astronomers attempted to reconstruct the distribution of mass in the object, revealing its so-called "density profile."

That's a highly complex procedure considering JVAS B1938+666 consists of many different bodies, the main component of which is a massive elliptical galaxy. Unlike those other bodies, however, the mysterious disruptor is completely invisible.

"Trying to separate all the different mass components of such a distant, low-mass object using gravitational lensing was extremely challenging and incredibly exciting," team leader Simona Vegetti of the Max Planck Institute for Astrophysics, Germany, said in a statement. "We're working with high-quality data and complex models, and just when I thought we had it all figured out, its properties threw up another surprise. "It's precisely this combination of difficulty and mystery that makes this object so fascinating."

What do we know about the mysterious disruptor so far?

To investigate the mysterious disruptor, Vegetti and colleagues first set about analyzing the small disturbances, or perturbations, that it makes to the overall arc of the gravitational lens JVAS B1938+666. They then compared data collected by an array of telescopes, including the Green Bank Telescope, to various models of dark matter. This revealed that none of these models could explain the mysterious disruptor.

"It has a very strange profile, because it's particularly dense at the center, but it extends enormously," team member Davide Massari of the National Institute for Astrophysics said. "So it's not uniformly distributed: it's as if there were an extremely compact object at the center, but then the profile continues to extend to distances much greater than those typically observed in galaxies or star systems of comparable mass."

Though investigations of the mysterious disruptor have thus far involved radio telescopes, future studies and a potential solution to this conundrum could come courtesy of telescopes operating in other wavelengths of light, including the powerful infrared vision of the James Webb Space Telescope (JWST)."If we were finally able to observe some form of light emission in the visible or infrared range, we could conclude, for example, that it is a somewhat anomalous ultracompact dwarf galaxy, with an unusually extended stellar halo," team member Cristiana Spingola of the National Institute for Astrophysics. "But if even with JWST we still fail to see starlight or other visible matter, then it would mean that we are dealing with an object whose properties are difficult to explain with current dark matter models."

The team's research was published on Monday (Jan.5) in the journal Nature Astronomy.

If dark matter particles decay, then scientists could hunt for signs of this process, including X-ray or gamma-ray radiation or even emitted "ghost particle" neutrinos, in vast clusters of galaxies.

Not only could this finally reveal what particles comprise mysterious dark matter, but it could also help astronomers understand the universe's structure like never before. And new research suggests that NASA's X-ray Imaging and Spectroscopy Mission (XRISM) could play an important role in this hunt.

Dark matter poses a significant challenge for scientists because, despite comprising around 85% of the matter in the cosmos, it remains effectively invisible. This is because it doesn't interact with electromagnetic radiation, or light — or, if it does, the interaction is too weak to be detected. This has led scientists to suggest a whole host of hypothetical particles to account for dark matter, which go beyond the standard model of particle physics and the electrons, protons and neutrons that make up the atoms that compose all everyday matter, like stars, planets, moons and our bodies.

One particular dark matter model suggests that whatever particles make up this mysterious stuff, they undergo a process called decay. This involves large particles breaking down over vast timescales to lighter particles, releasing energy in the form of photons, the particles of light. One possible signature of this process that astronomers could hunt for are X-ray photons released when decay occurs. In fact, scientists may have already spotted this cosmic fingerprint in the form of an unidentified X-ray emission in the light spectra from galaxy clusters.

"Eighty-five percent of mass in galaxy clusters comes from dark matter, and we can model the dark matter radial distribution well," study team member Ming Sun, of the University of Alabama in Huntsville (UAH), said in a statement. "Thus, galaxy clusters are great targets for such a search as they are dark matter-rich and we know the dark matter mass in clusters well."

In the past, researchers have relied on light-sensitive semiconductor chips called Charge-Coupled Devices (CCDs) to track the paths of possible decay particles to better understand what is causing this X-ray emission. However, Sun and colleagues took a different approach, instead turning to data from XRISM.

"Nearly all the past studies used the CCD data, which lack the required energy resolution to resolve the unidentified line," Sun said. "Now XRISM provides high-energy-resolution spectra that can resolve the line. As the line signals are very weak, we combined nearly three months of the XRISM data for such a search. There are many X-ray lines detected. They originate from known atoms, such as iron, silicon, sulfur, and nickel. X-ray emission lines that appear that are not at the known position of atomic lines are then the candidates for dark matter decay lines, which is the focus of this work."

The team theorizes that the leading suspects for this unknown emission are "sterile neutrinos." Neutrinos are virtually massless particles that stream through the cosmos at nearly the speed of light. The second-most abundant particle in the universe after photons, neutrinos are so "ghost-like" that 100 trillion pass through your body every single second, and you never notice a thing. Sterile neutrinos are one of the hypothetical particles that have been proposed to account for dark matter.

"A sterile neutrino is a hypothetical type of neutrino that only interacts with other particles via gravity, unlike the three known 'active' neutrinos that also interact via the weak force," Sun said. "The existence of the sterile neutrino is well-motivated theoretically and can explain the very small but non-zero mass of regular neutrinos. Sterile neutrinos can decay into two photons with the same energy. Models can predict the decay rate of sterile neutrinos, which is then constrained from the data."

Sterile neutrinos have a long way to go before they replace Weakly Interacting Massive Particles (WIMPs) as the leading suspects for dark matter, but Sun and colleagues are committed to exploring other possible candidates, including sterile neutrinos, even if that process includes ruling them out.

"WIMPs are still the leading candidate for dark matter, but billions of dollars of experiments have been done, only getting stronger and stronger upper limits, so alternative scenarios have to be considered. This study provides the strongest limits from high-energy-resolution data on the sterile neutrino at the 5 to 30 kiloelectronvolts (keV) band, subsequently limiting the models for dark matter," the UAH researcher concluded. "With more XRISM data in the next five to 10 years or so, we will be able to either detect the line or improve the limit substantially."

The team's research was published in November in The Astrophysical Journal Letters.

Using the Hubble Space Telescope, astronomers have discovered a new type of cosmic object, a cloud of dark matter and gas that contains no stars. The object, located around 14 million light-years from Earth at the outskirts of the spiral galaxy Messier 94 (M94), has been nicknamed "Cloud 9."

That's a fitting nickname, given the delight scientists would have if Cloud 9 lives up to its scientific potential. The new object could not only potentially help explain how galaxies formed from gatherings of dark matter in the early universe, but could also grant insights into the very nature of this most mysterious "stuff."

"This cloud is a window into the dark universe," team member Andrew Fox of the Association of Universities for Research in Astronomy/Space Telescope Science Institute (AURA/STScI) for the European Space Agency (ESA), said in a statement. "We know from theory that most of the mass in the universe is expected to be dark matter, but it’s difficult to detect this dark material because it doesn’t emit light. Cloud-9 gives us a rare look at a dark-matter-dominated cloud."

Dark matter is thought to account for around 85% of the "stuff" in the universe, but remains frustratingly invisible because it doesn't interact with electromagnetic radiation such as light. That means scientists can only infer the presence of dark matter via its interaction with gravity and the influence that interaction has on ordinary matter and on light.

Outweighing the particles that comprise the atoms that compose stars, planets, moons, and everything we see around us on a day-to-day basis, dark matter is believed to have had a major influence in the early cosmos and in the shape of the universe as we see it today. This includes the matter that led to the first stars and galaxies coming together in regions of intense gravity where dark matter first gathered.

Such should also be the case with Cloud 9. Within this dark matter-dominated cloud, known as aReionization-Limited Hydrogen I Cloud (RELHIC), hydrogen gas has at least begun to gather  — which would usually trigger stars being born from vast overdense patches in these clouds. However, star formation has failed to get started in the fossil remnant that is Cloud 9, likely because it seems to have failed to gather enough gas for star birth.

"This is a tale of a failed galaxy," team leader Alejandro Benitez-Llambay of the Milano-Bicocca University in Milan, Italy, said in NASA's statement. "In science, we usually learn more from the failures than from the successes. In this case, seeing no stars is what proves the theory right. It tells us that we have found in the local universe a primordial building block of a galaxy that hasn't formed."

Scientists have long theorized that RELHICs like this one exist, but they would have remained theoretical if it weren't for Hubble.

"Before we used Hubble, you could argue that this is a faint dwarf galaxy that we could not see with ground-based telescopes. They just didn't go deep enough in sensitivity to uncover stars," team member Gagandeep Anand of STScI said. "But with Hubble’s Advanced Camera for Surveys, we're able to nail down that there's nothing there."

The discovery of Cloud 9 indicates there may be many more relic-stalled galaxies out in the universe waiting to be uncovered.

"Among our galactic neighbors, there might be a few abandoned houses out there," said team member Rachael Beaton, also from STScI.

RELHICs aren't to be confused with hydrogen clouds around the Milky Way, which scientists have been studying for many years. Cloud-9 is smaller, more compact, and highly spherical, making it look very different from other hydrogen clouds. Its core is composed of neutral hydrogen and is around 4,900 light-years wide, with a mass estimated to be around 1 million times that of the sun. However, the mass of Cloud 9's dark matter has been estimated at around 5 billion solar masses.

The team behind this discovery thinks that Cloud 9 has the potential to become a fully-formed galaxy full of stars at some point in the future, but only if it can gather up to 5 billion solar masses of hydrogen gas. For now, the fact that it lacks stars means that Cloud 9 offers scientists a unique opportunity to study dark matter clouds.

Meanwhile, astronomers will now be paying close attention to future astronomical surveys in the hope of discovering more failed galaxy RELHICs.

The team's research was published in The Astrophysical Journal Letters and was presented at the 247th meeting of the American Astronomical Society in Phoenix on Monday (Jan. 5).

New research puts forward compelling new evidence that dark matter interacts with cosmic "ghost particles" called neutrinos. If that is the case, then this interaction could pose a serious challenge for the standard model of cosmology, our current best model of the universe.

Neutrinos earn their spooky nickname due to the fact that as these chargeless and virtually massless particles travel through space at near the speed of light, they barely interact with other particles, ghosting their way through solid objects like planets. In fact, the interactions between these particles and other matter are so rare and fleeting that every second, around 100 trillion neutrinos stream through your body without you feeling a thing. Dark matter is similar; even though it accounts for around 85% of the matter in the universe, whatever comprises dark matter also barely interacts with ordinary matter and light, if at all. In fact, effectively invisible, dark matter can only be inferred due to its interaction with gravity and the effect this has on light and conventional matter.

However, new findings from a team of researchers from the University of Sheffield suggest that a slight interaction, in the form of a minor exchange of momentum, exists between dark matter and neutrinos. That contradicts the so-called "Lambda Cold Dark Matter (LCDM)" model that attempts to explain the universe's structure and evolution, which says that dark matter and neutrinos exist independently and do not interact with each other.

The evidence for this potentially paradigm-shift-inducing suggestion comes from observations of the universe in its current state, conducted by the Dark Energy Camera on the Victor M. Blanco Telescope in Chile, from galaxy maps created by the Sloan Digital Sky Survey, and details of the universe's distant past gathered by both the Atacama Cosmology Telescope (ACT) and the European Space Agency (ESA) Planck Telescope spacecraft.

These observations have revealed that the modern universe is less "clumpy" than it should be. This cosmic conundrum could be explained by interactions between dark matter and neutrinos, which would impact the way cosmic structures like galaxies form and evolve.

"Our results address a long-standing puzzle in cosmology. Measurements of the early universe predict that cosmic structures should have grown more strongly over time than what we observe today," team member Eleonora Di Valentino of the University of Sheffield said in a statement. “However, observations of the modern universe indicate that matter is slightly less clumped than expected, pointing to a mild mismatch between early- and late-time measurements. This tension does not mean the standard cosmological model is wrong, but it may suggest that it is incomplete.

"Our study shows that interactions between dark matter and neutrinos could help explain this difference, offering new insight into how structure formed in the universe," Di Valentino added.

The next step is to test this idea, something that the team thinks is possible using precise observations from future telescopes of a cosmic fossil called the Cosmic Microwave Background (CMB), a leftover from an event in the universe shortly after the Big Bang. Astronomers could also test this theory using a specific effect that objects of great mass have on space, and therefore light, a phenomenon called "gravitational lensing." This would allow them to better measure the distribution of ordinary matter and dark matter.

"If this interaction between dark matter and neutrinos is confirmed, it would be a fundamental breakthrough," team member William Giarè of the University of Hawaii, said. "It would not only shed new light on a persistent mismatch between different cosmological probes, but also provide particle physicists with a concrete direction, indicating which properties to look for in laboratory experiments to help finally unmask the true nature of dark matter."

The team's research was published on Jan. 2 in the journal Nature Astronomy.

From distant exoplanets and the universe's first galaxies to the next generation of space telescopes, astronomy's biggest annual gathering is set to deliver a week of discoveries, debates and conversations that will shape the future of astronomy.

Thousands of astronomers, students, educators and space scientists are gathering in Phoenix, Arizona, this week as the 247th meeting of the American Astronomical Society (AAS 247) kicks off Monday — launching what many in the field consider the Super Bowl of astronomy. Running from Jan. 4–8 at the Phoenix Convention Center, the conference will feature panels, presentations and workshops covering everything from exoplanets and galaxy evolution to the future of flagship space telescopes.

Exoplanet research is expected to be a major focus, with sessions organized by NASA's Exoplanet Exploration Program Analysis Group examining the latest discoveries and debating priorities for future missions. Discussions around the proposed Habitable Worlds Observatory are likely to draw particular attention, as researchers explore how next-generation space telescopes could detect and characterize potential Earth-like planets around other stars beyond our solar system and identify biosignatures, or signs of life, in their atmospheres.

Cosmic origins and galaxy evolution will also be featured prominently throughout the week. Several sessions will showcase new results from surveys that combine data from the James Webb Space Telescope (JWST), Hubble Space Telescope and the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, offering fresh insights into how galaxies formed and evolved in the early universe. Other talks will dive into the nature of brown dwarfs, faint dwarf galaxies and the structure of the Milky Way's outskirts, highlighting how recent findings are reshaping long-standing theories.

Meanwhile, NASA's Program Analysis Groups (PAGs) — including those focused on cosmic origins, physics of the cosmos and exoplanet exploration — are meeting to brainstorm science goals, mission concepts and future priorities.

Looking ahead, astronomy's next major observatory, the Nancy Grace Roman Space Telescope, will be the subject of a dedicated Town Hall meeting on the status of the mission and next steps, as well as several other breakout sessions. As Roman edges closer to launch — currently planned for no earlier than September 2026 — scientists are refining how the mission's wide-field capabilities can complement JWST and ground-based observatories, particularly in studies of dark energy, exoplanets and infrared astrophysics.

Beyond the science itself, AAS 247 underscores the increasingly collaborative nature of modern astronomy. Sessions will highlight how skilled amateur astronomers are contributing to frontline research, while workshops and networking events aim to support early-career scientists navigating an evolving research landscape.

You can find a full list of scheduled events and topics for discussion in the program available online. Daily press conferences will also be held on-site and streamed live on Zoom, where virtual attendees can ask questions, and on the AAS Press Office YouTube channel.

2025 was an exciting year for astronomical discoveries. Scientists got the best evidence yet for past life on Mars, discovered an interstellar comet zooming through our solar system, found clues of possible nearby exoplanets, and much more. Here are eight of the most spectacular space stories from the past 12 months.

1. A new interstellar comet

The highlight from the second half of 2025 was undoubtedly Comet 3I/ATLAS, which is only the third interstellar object to have been discovered cruising through our solar system.

The Chilean component of the Asteroid Terrestrial-impact Last Alert System spotted the interstellar interloper sneaking among the stars of the constellation Sagittarius on July 1, and it quickly became apparent that its trajectory was severely hyperbolic. Rather than orbiting the sun like comets native to our solar system do, it was just passing through — and it was moving faster than any comet ever seen. Its abnormally high velocity of 36 miles per second (58 kilometers per second) told us that the speedy object, which became known as 3I/ATLAS, had probably been wandering interstellar space and receiving gravitational nudges from nearby stars since before our solar system even existed.

By September, 3I/ATLAS was moving behind the sun, making it impossible for Earth-based telescopes to track its movements until it reappeared in mid-November. Instead, NASA and the European Space Agency turned to their fleets of spacecraft that had better views of the comet during solar conjunction.

So far, we've learned that 3I/ATLAS is a comet and that all of its features have been seen on comets before. Its chemistry is broadly similar to the solar system's own comets, which is a profound discovery in its own right. There are a few differences, though — specifically, a slightly higher carbon-dioxide-to-water ratio, and a little more nickel than iron, which reflect the chemical composition of its star system of origin.

Besides a regular comet's tail, 3I/ATLAS has also sprouted an "anti-tail" — a short tail pointed toward the sun. Often, anti-tails are an optical illusion, but 3I/ATLAS' is real.

Astronomers will continue to track 3I/ATLAS into 2026 in the hope of learning more about its composition, but one thing is clear: It is a comet, not a spaceship.

Read more: New interstellar object 3I/ATLAS: Everything we know about the rare cosmic visitor

2. The birth of supermassive black holes

As soon as the James Webb Space Telescope (JWST) began taking deep images of the cosmos in 2022, it quickly started finding "little red dots" in the background. Astronomers didn't know what they were. At first they thought the dots could be dwarf galaxies or dense star clusters in the very early universe, but they were so luminous that the standard model of cosmology couldn't explain how they could have formed, prompting critics to suggest cosmology was broken.

However, the spectra of the little red dots didn't look like those of stars. In September, astronomers proposed an answer: The little red dots are "black hole stars" — supermassive black holes being born inside a huge, dense cloud of gas less than a billion years after the Big Bang.

These burgeoning supermassive black holes could have formed either by the direct gravitational collapse of a humongous gas cloud or from the merger of myriad stellar-mass black holes produced by the core collapse of massive stars in a dense stellar cluster hidden inside a gas cloud.

Nobody ever expected that those black holes would be produced by a whole new breed of object, so it's a crucial development in our understanding of black holes, the galaxies that eventually formed around them, and the early universe in general.

Read more: Are 'little red dots' seen by the James Webb Space Telescope actually elusive 'black hole stars'?

3. Weakening dark energy

The first full data release from the Dark Energy Spectroscopic Instrument (DESI), a state-of-the-art device on the Mayall Telescope at Kitt Peak in Arizona, came with shocking news: Dark energy, which is responsible for accelerating the expansion of the universe, seems to be weakening.

This was a direct contradiction of the leading hypothesis, which was that dark energy was the cosmological constant and, therefore, unchanging. While the new findings are not yet at the level of confidence required for astronomers to be sure the results are correct, they are significantly intriguing.

In 2024, some preliminary results from DESI pointed toward the strength of dark energy changing over time. Then, in March 2025, the DESI collaboration released data from the instrument's first three years of observations, spanning 13.1 million galaxies, 1.6 million quasars and about 4 million stars in relatively nearby galaxies, forming the largest and most accurate 3D map of the universe ever made.

The results showed that 4.5 billion years ago, dark energy seemed to begin weakening. Furthermore, during the previous 9 billion years, dark energy was stronger than anyone expected. This superpowered dark energy, dubbed phantom dark energy, invokes exotic physics. Why phantom dark energy would have transitioned into a weakening form two-thirds of the way into the universe's history is a complete mystery. Assuming the findings from DESI are correct, it would transform the way we view the past and future of the cosmos. For now, it deepens the mystery of dark energy.

Read more: Dark energy is even stranger than we thought, new 3D map of the universe suggests. 'What a time to be alive!' (video)

4. A year of biosignatures

Some of the most intriguing and controversial signs that we are not alone in the universe came to light in 2025, with discoveries on planets both near and far.

The best evidence yet for past life on Mars surfaced in September 2025, courtesy of NASA's Perseverance rover. That evidence was in the form of some light-red spots ringed by dark material. These "leopard spots" are not uncommon on rocks on Earth, and they typically form in one of two ways: either when exposed to hot, acidic conditions that have not been present in that part of Jezero crater, or through biological action. Organic molecules were also discovered in clay sediments within the rock, although Perseverance was unable to identify these molecules. The discovery is the most compelling evidence yet that microbial life could have existed in Jezero crater 3.5 billion years ago.

A more recent biosignature was potentially found on the exoplanet K2-18b by astronomers using JWST. In 2023, a team found signs of the gas dimethyl sulfide, alongside methane and oxygen. The team thinks this finding suggests K2-18b is a "hycean" planet — a world with an incredibly deep global ocean of water, surrounded by a thick, hydrogen-rich atmosphere. The team predicted that dimethyl sulfide could be a biosignature on a hycean world, as it can be on Earth, but the initial detection was very tentative. In March 2025, JWST produced stronger evidence for dimethyl sulfide's existence on K2-18b.

Even so, many astronomers are still skeptical of the discovery. Some argue against the concept of hycean worlds, point out that the signal is very weak, and raise the possibility that dimethyl sulfide can also form abiotically.

Read more: Did NASA's Perseverance rover find evidence of ancient life on Mars? The plot thickens

5. New exoplanetary neighbors

This year, astronomers made major steps in adding to the exoplanet inventory around the nearest stars, Alpha-Proxima Centauri and Barnard's Star.

Astronomers had previously thought they'd found planets in both systems, but each time, the evidence didn't hold up. Then, in 2024, a strong candidate for a small, rocky planet orbiting Barnard's Star was revealed in data from the Very Large Telescope in Chile. In March 2025, this observation was confirmed to be real, along with those of three smaller exoplanets. The most massive of the quartet has one-third the mass of Earth, while the smallest is one-fifth the mass of our planet. Unfortunately, none reside in the habitable zone, but further planets in more temperate regions have not been ruled out.

Then, in August, observations by JWST produced the most convincing evidence yet for a planet orbiting Alpha Centauri A. The exoplanet is estimated to have a mass similar to that of Saturn and, therefore, expected to be a gas giant. Intriguingly, if this world is real, it must have a highly elliptical orbit that may result from its inclusion in a binary system.

Read more: 4 rocky exoplanets found around Barnard's Star, one of the sun's nearest neighbors

James Webb Space Telescope spots a potential new exoplanet just 4 light-years away from Earth

6. The Milky Way and Andromeda's uncertain future

The Milky Way and Andromeda galaxies might not crash into each other in the next 10 billion years after all. New research published this year finds that there is a 50-50 chance that the two galaxies will miss each other.

By considering the way the Large Magellanic Cloud's gravity pulls on the Milky Way and how the gravity of the Triangulum Galaxy pulls on Andromeda, researchers refined how close Andromeda and the Milky Way galaxies will get by running a multitude of simulations.

They found that the critical distance is 650,000 light years. If they pass closer than that, the two galaxies will collide at some point in the next 10 billion years. If their closest approach is greater than 650,000 light years, they won't make contact. According to the simulations, both possibilities are equally likely.

Read more: The Milky Way may not collide with neighboring galaxy Andromeda after all: 'From near-certainty to a coin flip'

7. The most massive black hole ever seen?

In 2025, astronomers may have discovered the most massive black hole ever seen. This ultra-massive black hole, which tips the scales at 36 billion solar masses, resides at the heart of one of the most massive galaxies in the universe, called the Cosmic Horseshoe because it acts as a gravitational lens that bends the light of a more distant galaxy into an Einstein ring sporting a horseshoe shape.

More massive black holes have been claimed, but the authors of the new research pointed out that those other black holes had their masses measured indirectly, so their masses are just guesses. The mass of the black hole in the Cosmic Horseshoe, on the other hand, has been measured directly and more accurately by tracking the motion of groups of stars around it, pulled by the black hole's gravity. It certainly puts our 4.1 million-solar mass supermassive black hole, Sagittarius A*, in the shade.

Read more: The biggest black hole ever seen? Scientists find one with mass of 36 billion suns

8. First light for the Vera C. Rubin Observatory

After more than a quarter century of planning and over 10 years of construction, the Vera C. Rubin Observatory in Chile, armed with its 8.4-meter (27.6 feet) Simonyi Survey Telescope, saw first light in the summer of 2025 — and its images of the heavens were exquisite.

The telescope is designed for high-resolution surveys, with studies of dark matter and dark energy in mind. Two areas of the sky were targeted for first light to demonstrate the telescope's prowess. One was the mighty Virgo Cluster, whose member galaxies had never been seen so clearly across such a wide expanse of space, and with 10 million faint galaxies in the background to boot. The other image was of the Trifid and Lagoon nebulas, two star-forming regions in the Milky Way.

Each night, the telescope will capture 20TB of data with its 3.2-gigapixel CCD camera — the largest ever built — and issue 10 million alerts daily for asteroids, variable stars, tidal disruption events and supernovas. Over the course of its initial 10-year Legacy Survey of Space and Time, the observatory will accumulate 60 petabytes (60,000TB) of information. With all that data, the Rubin Observatory may deliver a tsunami of unprecedented astronomical discoveries.

Read more: Vera C Rubin Observatory reveals 1st stunning images of the cosmos. Scientists are 'beyond excited about what's coming'

Exotic, dark astrophysical objects may be hiding in interstellar space, and a new proposal outlines how to find them: stare really, really hard.

We don't know what dark matter is, even though we strongly suspect it exists. We see circumstantial evidence for it everywhere, from the rotation rates of galaxies to the growth of the largest structures in the cosmos. For decades, cosmologists have thought dark matter is some sort of exotic particle that was previously unknown to the Standard Model of particle physics. This strange particle would not interact with light, or really much of anything else, except through its gravitational influence.

But searches for these dark matter particles have come up empty so far, driving theorists to get more creative with their ideas.

It could be that dark matter isn't made of zillions of tiny particles flying through the universe. Instead, it could be composed of bunched-up collections of much larger objects. In particular, the researchers behind a new study, published in November 2025 in the open access server arXiv, investigated two kinds of exotic objects.

The first is known as a boson star. In this model, dark matter is made of an ultra-ultra-ultra light particle — potentially millions of times lighter than neutrinos, the lightest known particles. They would be so light that their quantum nature would make them appear more like waves at galactic scales than like individual particles. But these waves would sometimes bunch up and collect on themselves, pulling together with their own gravity, without collapsing.

Another possibility is called Q-balls. In this model, dark matter isn't a particle at all but rather a quantum field that soaks all of space and time. Due to a special property of this field, it could occasionally pinch off, creating gigantic, stable, lump-like balls that wander the cosmos like a floating piece of flour in gravy that hasn't been mixed well.

Both boson stars and Q-balls, which live under the more general heading of exotic astrophysical dark objects (EADOs), are difficult to detect. They're large — roughly star-size — but they do not emit light of their own, making them nearly invisible in our scans of the cosmos.

But astronomers have discovered a way that EADOs can betray their presence: microlensing. If a Q-ball or boson star were to pass between us and a distant star, the strong gravity of the EADO would cause the light from the star to act as a gravitational lens. From our perspective, it would make the star appear to suddenly jump into position and then quickly return to normal.

So all we'd have to do is stare at a whole bunch of stars for a really long time and hope we get lucky. Thankfully, we have just the instrument for the job. The Gaia space telescope's mission was to do just that: stare at a whole bunch of stars for a really long time.

The astronomers behind the study propose a campaign using Gaia data to search for Q-balls and boson stars by looking for their unique, "smoking gun" signal of sudden jumps in stellar positions. Depending on how many are out there, Gaia may have observed up to several thousand EADOs.

But if they're not out there, then this same campaign would produce stringent limits on Q-balls' and boson stars' contributions to the overall dark matter picture. No matter what, staring into the dark would teach us something.

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

If you look across space with a telescope, you'll see countless galaxies, most of which host large central black holes, billions of stars and their attendant planets. The universe teems with huge, spectacular objects, and it might seem like these massive objects should hold most of the universe's matter.

But the Big Bang theory predicts that about 5% of the universe's contents should be atoms made of protons, neutrons and electrons. Most of those atoms cannot be found in stars and galaxies – a discrepancy that has puzzled astronomers.

If not in visible stars and galaxies, the most likely hiding place for the matter is in the dark space between galaxies. While space is often referred to as a vacuum, it isn't completely empty. Individual particles and atoms are dispersed throughout the space between stars and galaxies, forming a dark, filamentary network called the "cosmic web."

Throughout my career as an astronomer, I've studied this cosmic web, and I know how difficult it is to account for the matter spread throughout space.

In a study published in June 2025, a team of scientists used a unique radio technique to complete the census of normal matter in the universe.

The census of normal matter

The most obvious place to look for normal matter is in the form of stars. Gravity gathers stars together into galaxies, and astronomers can count galaxies throughout the observable universe.

The census comes to several hundred billion galaxies, each made of several hundred billion stars. The numbers are uncertain because many stars lurk outside of galaxies. That's an estimated 10²³ stars in the universe, or hundreds of times more than the number of sand grains on all of Earth's beaches. There are an estimated 10⁸² atoms in the universe.

However, this prodigious number falls far short of accounting for all the matter predicted by the Big Bang. Careful accounting indicates that stars contain only 0.5% of the matter in the universe. Ten times more atoms are presumably floating freely in space. Just 0.03% of the matter is elements other than hydrogen and helium, including carbon and all the building blocks of life.

Looking between galaxies

The intergalactic medium – the space between galaxies – is near-total vacuum, with a density of one atom per cubic meter, or one atom every 35 cubic feet. That's less than a billionth of a billionth of the density of air on Earth. Even at this very low density, this diffuse medium adds up to a lot of matter, given the enormous, 92-billion-light-year diameter of the universe.

The intergalactic medium is very hot, with a temperature of millions of degrees. That makes it difficult to observe except with X-ray telescopes, since very hot gas radiates out through the universe at very short X-ray wavelengths. X-ray telescopes have limited sensitivity because they are smaller than most optical telescopes.

Deploying a new tool

Astronomers recently used a new tool to solve this missing matter problem. Fast radio bursts are intense blasts of radio waves that can put out as much energy in a millisecond as the Sun puts out in three days. First discovered in 2007, scientists found that the bursts are caused by compact stellar remnants in distant galaxies. Their energy peters out as the bursts travel through space, and by the time that energy reaches the Earth, it is a thousand times weaker than a mobile phone signal would be if emitted on the moon, then detected on Earth.

Research from early 2025 suggests the source of the bursts is the highly magnetic region around an ultra-compact neutron star. Neutron stars are incredibly dense remnants of massive stars that have collapsed under their own gravity after a supernova explosion. The particular type of neutron star that emits radio bursts is called a magnetar, with a magnetic field a thousand trillion times stronger than the Earth's.

Even though astronomers don't fully understand fast radio bursts, they can use them to probe the spaces between galaxies. As the bursts travel through space, interactions with electrons in the hot intergalactic gas preferentially slow down longer wavelengths. The radio signal is spread out, analogous to the way a prism turns sunlight into a rainbow. Astronomers use the amount of spreading to calculate how much gas the burst has passed through on its way to Earth.

Puzzle solved

In the new study, published in June 2025, a team of astronomers from Caltech and the Harvard Center for Astrophysics studied 69 fast radio bursts using an array of 110 radio telescopes in California. The team found that 76% of the universe's normal matter lies in the space between galaxies, with another 15% in galaxy halos – the area surrounding the visible stars in a galaxy – and the remaining 9% in stars and cold gas within galaxies.

The complete accounting of normal matter in the universe provides a strong affirmation of the Big Bang theory. The theory predicts the abundance of normal matter formed in the first few minutes of the universe, so by recovering the predicted 5%, the theory passes a critical test.

Several thousand fast radio bursts have already been observed, and an upcoming array of radio telescopes will likely increase the discovery rate to 10,000 per year. Such a large sample will let fast radio bursts become powerful tools for cosmology. Cosmology is the study of the size, shape and evolution of the universe. Radio bursts could go beyond counting atoms to mapping the three-dimensional structure of the cosmic web.

Pie chart of the universe

Scientists may now have the complete picture of where normal matter is distributed, but most of the universe is still made up of stuff they don't fully understand.

The most abundant ingredients in the universe are dark matter and dark energy, both of which are poorly understood. Dark energy is causing the accelerating expansion of the universe, and dark matter is the invisible glue that holds galaxies and the universe together.

Dark matter is probably a previously unstudied type of fundamental particle that is not part of the standard model of particle physics. Physicists haven't been able to detect this novel particle yet, but we know it exists because, according to general relativity, mass bends light, and far more gravitational lensing is seen than can be explained by visible matter. With gravitational lensing, a cluster of galaxies bends and magnifies light in a way that's analogous to an optical lens. Dark matter outweighs conventional matter by more than a factor of five.

One mystery may be solved, but a larger mystery remains. While dark matter is still enigmatic, we now know a lot about the normal atoms making up us as humans, and the world around us.

How do you search for invisible hypothetical particles? One way is to see how quickly they could kill white dwarfs — the dense, leftover cores of dead stars.

In recent years, astronomers have become increasingly interested in a theoretical particle known as the axion, which was concocted decades ago to solve a challenging problem with the strong nuclear force. After initial attempts to find it in particle collider experiments turned up empty, however, the idea sunk into the background.

But further research revealed that the axion could be a contender to explain the mystery of dark matter. Theorists realized that there might be ways for axions to flood the universe but so far evade direct detection.

Just because this little particle would be largely invisible, it doesn't mean it would go completely unnoticed in the universe. In a pre-print paper published in November 2025 in the open access server arXiv, researchers reported a way to test axion models using old archival data from the Hubble Space Telescope. Although they didn't find any evidence for axions, they beat other attempts and gave us a much clearer picture of what is and isn't allowed in this universe.

The targets for this study were white dwarfs — the dense, dim cores of dead stars. A single white dwarf can pack the mass of the sun into an object smaller than Earth, making white dwarfs among the most exotic objects in the universe. Crucially, white dwarfs support themselves against collapse through something called electron degeneracy pressure, in which a huge sea of free-floating electrons resists collapse because, according to quantum mechanics, electrons can never share the same state.

Some models of how axions might behave say these particles could be created by electrons: If an electron were moving quickly enough, it would trigger the formation of an axion. And because the electrons deep inside a white dwarf are moving very, very quickly — at nearly the speed of light — as they buzz around in their tight confines, they could produce a lot of axions.

The axions would then go speeding off, leaving the white dwarf altogether. This production of escaping axions would rob the white dwarf of energy. And because white dwarfs don't produce energy on their own, this would cause them to cool off faster than they would otherwise.

The researchers fed this model of axion cooling into a sophisticated software suite that can simulate the evolution of stars and how their temperature and brightness change as their interiors evolve.

This model allowed the researchers to predict the typical temperature of a white dwarf, given its age, both with and without axion cooling. With the results in hand, they turned to data of the globular cluster 47 Tucanae collected with Hubble. Global clusters are crucial because all of the white dwarfs in them were born at roughly the same time, giving the astronomers a large sample to study.

In short, the researchers found no evidence for axion cooling in the white dwarf population. But their results did give brand-new constraints on the ability for electrons to produce axions: They can't do it more efficiently than once every trillion chances.

This result doesn't rule out axions entirely, but it does say it's unlikely that electrons and axions directly interact with each other. So, if we're going to keep searching for axions, we're going to have to find even more clever ways to look.

Since it began operations in 2022, the James Webb Space Telescope (JWST) has allowed scientists to make incredible strides in our understanding of the cosmos  — especially its early epoch. However, one lingering cosmological mystery that the JWST hasn't had a major impact on is the nature of dark matter. Now, new research suggests that this is something that may soon change.

While dark matter is estimated to account for 85% of the matter in the universe, it is difficult to investigate because it doesn't interact with electromagnetic radiation (light) or it interacts so weakly that we can't directly detect it. As well as making dark matter effectively invisible, this lack of interaction with light tells scientists that the particles making up dark matter aren't the protons, neutrons, and electrons that comprise the everyday stuff we see around us on a day-to-day basis, ranging from the most massive stars to the viruses that make our lives miserable every winter. The search for a potential dark matter particle has delivered many suspects, but they've all remained frustratingly hypothetical.

Thus, the only way scientists can infer the presence of dark matter is by looking at the gravitational influence it has on the fabric of space and how this then impacts ordinary matter and light. This new research, published in the journal Nature Astronomy, suggests that the gravitational influence of dark matter may be the cause of strange young galaxies with unexpectedly elongated shapes. And investigating these shapes could reveal which of these hypothetical particles is the best recipe for dark matter.

Studying these elongated galaxies with the JWST might help reveal the presence of dark matter, scientists say. "In the expanding universe defined by Einstein’s theory of general relativity, galaxies grow over time from small clumps of dark matter that form the first star clusters and assemble into larger galaxies via their collective gravity," team member Rogier Windhorst, of Arizona State University, said in a statement.

"But now the JWST suggests that the earliest galaxies may be embedded in marked filamentary structures, which — unlike cold, dark matter — smoothly join the star-forming regions together, more akin to what is expected if dark matter is an ultralight particle that also shows quantum behavior."

Understanding dark matter is a stretch

When using simulations to recreate how the first galaxies formed in the early universe, allowing cool gas to gather along the threads in a web of dark matter is able to quite nicely recreate the mostly spheroid galaxies we see in the modern universe.

However, as the JWST has been allowing astronomers to look back at galaxies that existed in the very early stages of the universe, they have increasingly been finding filamentary elongated galaxies that aren't as easily recreated in simulations that stick to the standard mechanism of gas gathering to birth stars and grow galaxies.

To investigate this, Windhorst and colleagues looked at simulations of the universe involving different types of dark matter other than that found in the most accepted model of cosmology, the Lambda Cold Dark Matter (LCDM) model; "cold" dark matter, which doesn't refer to temperature but instead to the speed at which particles move.

This revealed that the wave-like behavior of "fuzzy dark matter" or ultralight axion particles could account for the elongated morphology of early galaxies seen by the JWST.

"If ultralight axion particles make up the dark matter, their quantum wave-like behavior would prevent physical scales smaller than a few light-years from forming for a while, contributing to the smooth filamentary behavior that JWST now sees at very large distances," team leader Álvaro Pozo of the Donostia International Physics Center said.

The team's modelling also indicated that faster-moving "warm dark matter" particles, like sterile neutrinos, could also give rise to early filamentary galaxies. In both the wave dark matter and warm dark matter scenarios, this is because these particles give rise to smoother filaments than cold dark matter. As gas and stars slowly flow down these filaments, elongated galaxies begin to form.

The JWST will continue to investigate oddly shaped galaxies in the early universe, while researchers here on Earth continue to evolve simulations of the early universe. Bringing these together could eventually help solve the mystery of dark matter.

The team's research was published on Dec. 8 in the journal Nature Astronomy.

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

Scientists working with the James Webb Space Telescope discovered three unusual astronomical objects in early 2025, which may be examples of dark stars. The concept of dark stars has existed for some time and could alter scientists' understanding of how ordinary stars form. However, their name is somewhat misleading.

"Dark stars" is one of those unfortunate names that, on the surface, does not accurately describe the objects it represents. Dark stars are not exactly stars, and they are certainly not dark.

Still, the name captures the essence of this phenomenon. The "dark" in the name refers not to how bright these objects are, but to the process that makes them shine — driven by a mysterious substance called dark matter. The sheer size of these objects makes it difficult to classify them as stars.

As a physicist, I've been fascinated by dark matter, and I've been trying to find a way to see its traces using particle accelerators. I'm curious whether dark stars could provide an alternative method to find dark matter.

What makes dark matter dark?

Dark matter, which makes up approximately 27% of the universe but cannot be directly observed, is a key idea behind the phenomenon of dark stars. Astrophysicists have studied this mysterious substance for nearly a century, yet we haven't seen any direct evidence of it besides its gravitational effects. So, what makes dark matter dark?

Humans primarily observe the universe by detecting electromagnetic waves emitted by or reflected off various objects. For instance, the moon is visible to the naked eye because it reflects sunlight. Atoms on the moon's surface absorb photons – the particles of light – sent from the sun, causing electrons within atoms to move and send some of that light toward us.

More advanced telescopes detect electromagnetic waves beyond the visible spectrum, such as ultraviolet, infrared or radio waves. They use the same principle: Electrically charged components of atoms react to these electromagnetic waves. But how can they detect a substance – dark matter – that not only has no electric charge but also has no electrically charged components?

Although scientists don't know the exact nature of dark matter, many models suggest that it is made up of electrically neutral particles – those without an electric charge. This trait makes it impossible to observe dark matter in the same way that we observe ordinary matter.

Dark matter is thought to be made of particles that are their own antiparticles. Antiparticles are the "mirror" versions of particles. They have the same mass but opposite electric charge and other properties. When a particle encounters its antiparticle, the two annihilate each other in a burst of energy.

If dark matter particles are their own antiparticles, they would annihilate upon colliding with each other, potentially releasing large amounts of energy. Scientists predict that this process plays a key role in the formation of dark stars, as long as the density of dark matter particles inside these stars is sufficiently high. The dark matter density determines how often dark matter particles encounter, and annihilate, each other. If the dark matter density inside dark stars is high, they would annihilate frequently.

What makes a dark star shine?

The concept of dark stars stems from a fundamental yet unresolved question in astrophysics: How do stars form? In the widely accepted view, clouds of primordial hydrogen and helium — the chemical elements formed in the first minutes after the Big Bang, approximately 13.8 billion years ago — collapsed under gravity. They heated up and initiated nuclear fusion, which formed heavier elements from the hydrogen and helium. This process led to the formation of the first generation of stars.

In the standard view of star formation, dark matter is seen as a passive element that merely exerts a gravitational pull on everything around it, including primordial hydrogen and helium. But what if dark matter had a more active role in the process? That’s exactly the question a group of astrophysicists raised in 2008.

In the dense environment of the early universe, dark matter particles would collide with, and annihilate, each other, releasing energy in the process. This energy could heat the hydrogen and helium gas, preventing it from further collapse and delaying, or even preventing, the typical ignition of nuclear fusion.

The outcome would be a starlike object — but one powered by dark matter heating instead of fusion. Unlike regular stars, these dark stars might live much longer because they would continue to shine as long as they attracted dark matter. This trait would make them distinct from ordinary stars, as their cooler temperature would result in lower emissions of various particles.

Can we observe dark stars?

Several unique characteristics help astronomers identify potential dark stars. First, these objects must be very old. As the universe expands, the frequency of light coming from objects far away from Earth decreases, shifting toward the infrared end of the electromagnetic spectrum, meaning it gets "redshifted." The oldest objects appear the most redshifted to observers.

Since dark stars form from primordial hydrogen and helium, they are expected to contain little to no heavier elements, such as oxygen. They would be very large and cooler on the surface, yet highly luminous because their size — and the surface area emitting light — compensates for their lower surface brightness.

They are also expected to be enormous, with radii of about tens of astronomical units — a cosmic distance measurement equal to the average distance between Earth and the sun. Some supermassive dark stars are theorized to reach masses of roughly 10,000 to 10 million times that of the sun, depending on how much dark matter and hydrogen or helium gas they can accumulate during their growth.

So, have astronomers observed dark stars? Possibly. Data from the James Webb Space Telescope has revealed some very high-redshift objects that seem brighter — and possibly more massive — than what scientists expect of typical early galaxies or stars. These results have led some researchers to propose that dark stars might explain these objects.

Dark stars may explain early black holes

What happens when a dark star runs out of dark matter? It depends on the size of the dark star. For the lightest dark stars, the depletion of dark matter would mean gravity compresses the remaining hydrogen, igniting nuclear fusion. In this case, the dark star would eventually become an ordinary star, so some stars may have begun as dark stars.

Supermassive dark stars are even more intriguing. At the end of their lifespan, a dead supermassive dark star would collapse directly into a black hole. This black hole could start the formation of a supermassive black hole, like the kind astronomers observe at the centers of galaxies, including our own Milky Way.

Dark stars might also explain how supermassive black holes formed in the early universe. They could shed light on some unique black holes observed by astronomers. For example, a black hole in the galaxy UHZ-1 has a mass approaching 10 million solar masses, and is very old – it formed just 500 million years after the Big Bang. Traditional models struggle to explain how such massive black holes could form so quickly.

The idea of dark stars is not universally accepted. These dark star candidates might still turn out just to be unusual galaxies. Some astrophysicists argue that matter accretion — a process in which massive objects pull in surrounding matter — alone can produce massive stars, and that studies using observations from the James Webb telescope cannot distinguish between massive ordinary stars and less dense, cooler dark stars.

Researchers emphasize that they will need more observational data and theoretical advancements to solve this mystery.

NASA's Nancy Grace Roman Space Telescope is now fully assembled and ready to begin launch preparations this summer.

The final integration of the telescope's major observatory components took place on Nov. 25 inside NASA's Goddard Space Flight Center in Greenbelt, Maryland, where engineers brought together the spacecraft and telescope assemblies in the facility's largest clean room, according to a statement from NASA.

"Completing the Roman observatory brings us to a defining moment for the agency," Amit Kshatriya, NASA Associate Administrator, said in the statement. "Transformative science depends on disciplined engineering, and this team has delivered — piece by piece, test by test — an observatory that will expand our understanding of the universe. As Roman moves into its final stage of testing following integration, we are focused on executing with precision and preparing for a successful launch on behalf of the global scientific community."

Roman is designed to survey the universe with unprecedented efficiency using two primary instruments: the Wide Field Instrument (WFI) — a powerful infrared camera with a field of view larger than that of the Hubble Space Telescope at comparable resolution — and a next-generation Coronagraph Instrument that will image exoplanets by blocking light from distant stars, making it easier to see the planets in orbit around them. Together, these instruments will map cosmic structures on grand scales, probe dark energy, measure the distribution of dark matter, detect isolated black holes through microlensing and identify potentially tens of thousands of distant exoplanets, according to the statement.

With physical construction complete, Roman now shifts into a lengthy campaign of environmental and performance testing under simulated space conditions designed to verify that the spacecraft can survive the stresses of launch and operate as intended once in space. After that, the telescope will be shipped to NASA's Kennedy Space Center in Florida this summer for final processing and integration with its launch vehicle. While the mission is slated to launch by May 2027, it could be ready as early as fall 2026, NASA officials said.

If all goes as planned, Roman will launch aboard a SpaceX Falcon Heavy rocket to a gravitationally stable orbit around the sun nearly a million miles from Earth. During its planned five-year primary mission, Roman is expected to observe billions of galaxies and hundreds of millions of stars, providing new clues about the accelerating expansion of the universe. Mission scientists also expect the telescope to detect more than 100,000 exoplanets by monitoring subtle gravitational lensing events, whereby a larger foreground object magnifies the light from a more distant source that cannot otherwise be observed directly.

"With Roman's construction complete, we are poised at the brink of unfathomable scientific discovery," Julie McEnery, Roman's senior project scientist at NASA Goddard, said in the statement. "We stand to learn a tremendous amount of new information about the universe very rapidly after Roman launches."

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Galaxies residing in a huge filament of dark matter have been found to be mostly rotating in the same direction that the filament is spinning. It's a discovery that challenges what astronomers think they know about how the environment influences galactic evolution.

The filament is a thread in the cosmic web, which is made of mostly dark matter and laced with ordinary matter, that spans the entire universe. Located 140 million light-years away, the filament has a nested structure. At its heart is a row of 14 galaxies almost precisely placed in a line 5.5 million light years long and 117,000 light-years wide, and all are rich in hydrogen gas that's required for forming stars. This row of galaxies is then embedded in the larger filament that's 50 million light years in length and is home to about 300 galaxies in total.

The row of galaxies is extraordinary not because they are aligned in a narrow band, but because many of them are rotating in the same direction as the filament itself. Think of each galaxy, slowly rotating around its axis, and then picture those galaxies perpendicular to the long axis of the filament and rotating about that spindle at 68 miles (110 kilometers) per second in the same direction as they themselves are spinning on their axis. All together, it is one of the largest cohesive rotating structures known in the universe.

"What makes this structure exceptional is not just its size, but the combination of spin alignment and rotational motion," Lyla Jung of the University of Oxford said in a statement. "You can liken it to the teacups ride at a theme park. Each galaxy is like a spinning teacup, but the whole platform – the cosmic filament — is rotating too. This dual motion gives us rare insight into how galaxies gain their spin from the larger structures they live in."

Jung and Madalina Tudorache, also at Oxford, co-led the study into the filament using the 64 networked dishes of the MeerKAT radio telescope in South Africa to track the motion of the neutral hydrogen gas in the galaxies and the filament, combined with optical data from the Dark Energy Spectroscopic Instrument at the Kitt Peak National Observatory in Arizona and the Sloan Digital Sky Survey in New Mexico.

In 2022, astronomers discovered that filaments in the cosmic web are rotating, based on the motion of the galaxies within them. This new discovery that the galaxies themselves spin on their axis in the same direction as the filament rotates is surprising because of how astronomers think galaxies form in the first place.

The gas, stars and dust in the Milky Way galaxy, for example, are all rotating around the galactic center. It will take our sun and solar system 220 million years to complete one orbit of the galaxy. The rotation of a galaxy is partly a legacy of the spinning cloud of gas that originally formed it 13 billion years ago, the cloud passing its angular momentum on to the galaxy. However, since then most galaxies have experienced close encounters, collisions and full-on mergers with other galaxies that can disrupt how they spin.

However, the rotation of this filament clearly dominates how the galaxies within it spin, perhaps by funneling hydrogen gas along the dark-matter filament and onto the galaxies in a way that coerces their spin while providing further fuel for star formation.

"This filament is a fossil record of cosmic flows," said Tudorache. "It helps us piece together how galaxies acquire their spin and grow over time."

The galaxies in the filament also seem relatively young and in an early stage of development; it's possible that their spins could alter as they mature.

That flows of material along cosmic filaments can influence the properties of galaxies to this degree is a surprise though, and will lead to important modifications in models of how galaxies form.

Such alignments could also influence measurements made as part of weak lensing surveys, such as that to be performed by the Legacy Survey of Space and Time on the Vera C. Rubin Observatory in Chile, which is about to begin work after revealing its first-light images this past summer. Weak lensing surveys look for distortions in the shapes and alignments of galaxies caused by the subtle gravitational lensing by dark matter to allow astronomers to map the cosmic web. Understanding more about how galaxies align and rotate along those filaments will help lead to more accurate measurements.

The discovery of the alignment of galaxies in the spinning filament was reported on Dec. 4 in the journal Monthly Notices of the Royal Astronomical Society.

Scientists may have "seen" dark matter for the first time, thanks to NASA's Fermi gamma-ray space telescope. If so, this would mark the first direct detection of the universe's most mysterious substance.

Dark matter was theorized in 1933 by astronomer Fritz Zwicky, who found that the visible galaxies of the Coma Cluster lacked the necessary gravitational influence to prevent this cluster from flying apart. Then, in the 1970s, astronomer Vera Rubin and colleagues found the outer edges of spiral galaxies were spinning at the same rate as their centers, something that would only be possible if the major amount of mass in these galaxies wasn't concentrated at their centers, but rather more widely dispersed. These aren't direct observations of dark matter, of course, but inferences made using dark matter's interactions with gravity as well as the influence gravity then has on ordinary matter and light. Still, because of these findings, s astronomers have since calculated that all large galaxies are embedded within vast haloes of dark matter that expand way beyond the limits of visible matter in galaxies (such as galactic haloes of stars).

The particles of this mysterious substance are now estimated to outweigh the particles that make up everyday matter by a ratio of five to one. That means everything we see around us on a day-to-day basis — stars, planets, moons, our bodies, next door's cat, and so on — all account for just 15% of the matter in the universe, with dark matter accounting for the other 85%. Adding to the mystery of dark matter is the fact that, because it interacts with electromagnetic radiation so weakly, or not at all, it doesn't emit, absorb, or reflect light. Thus, it is effectively invisible in all wavelengths of light — or at least, we thought it was.

There is one possibility that would result in dark matter producing light. If dark matter particles "annihilate" when they meet each other and interact, much as matter and its counterpart antimatter do, then it should produce a shower of particles, including photons of gamma-rays that, while invisible to our eyes, could be "seen" by sensitive gamma-ray space telescopes. One of the suggested "self-annihilating" particles theorized to comprise dark matter are so-called "Weakly Interacting Massive Particles" or "WIMPS."

A team of researchers, led by Tomonori Totani from the Department of Astronomy at the University of Tokyo, trained the Fermi spacecraft on the regions of the Milky Way where dark matter should congregate, namely at the center of our galaxy, and hunted for this telltale gamma-ray signature.

Well, Totani thinks we finally found that signature.

"We detected gamma rays with a photon energy of 20 gigaelectronvolts (or 20 billion electronvolts, an extremely large amount of energy) extending in a halolike structure toward the center of the Milky Way galaxy," Totani said. "The gamma-ray emission component closely matches the shape expected from the dark matter halo."

And this isn't the only close match. The energy signature of these gamma-rays closely matches those predicted to emerge from the annihilation of colliding WIMPs, which are predicted to have a mass around 500 times that of a proton, the ordinary matter particles found at the heart of atoms. Totani suggests there aren't any other astronomical phenomena that easily explain the gamma-rays observed by Fermi.

"If this is correct, to the extent of my knowledge, it would mark the first time humanity has ‘seen’ dark matter. And it turns out that dark matter is a new particle not included in the current standard model of particle physics," Totani said. "This signifies a major development in astronomy and physics."

While Totani is confident that what he and his colleagues have detected is the signature of dark matter WIMPs annihilating each other at the heart of the Milky Way, the scientific community in general will require more hard evidence before the book is closed on this nearly century-old mystery.

"This may be achieved once more data is accumulated, and if so, it would provide even stronger evidence that the gamma rays originate from dark matter," Totani added.

The team's research was published on Tuesday (Nov. 25) in the Journal of Cosmology and Astroparticle Physics.

Scientists have discovered that dark matter, the universe's most mysterious "stuff," obeys gravity on vast cosmological scales. This could help to dismiss the possibility of a fifth fundamental force of nature — but even if not, it certainly puts restraints on that potential force's strength.

It's long been known that "everyday matter" is made up of atoms, which are, in turn, composed of protons, neutrons and electrons. We also know that these particles fall in line with the known fundamental forces of nature: electromagnetism, gravity, the strong nuclear force and the weak nuclear force. However, what has been less clear is whether dark matter obeys these same four forces. Indeed, one of the reasons dark matter is so puzzling is that it doesn't seem to act in conjunction with light, or electromagnetic radiation. And if it does, it does so much more weakly than ordinary matter does. This makes dark matter effectively invisible, meaning the only way scientists can infer its presence is by observing its gravitational effects and then watching how that acts as a middleman and impacts light and ordinary matter.

But determining that dark matter interacts gravitationally on relatively small scales, such as within galaxies, doesn't tell us if it obeys the well-understood laws of gravity as defined by Albert Einstein's 1915 theory of gravity, general relativity, on much larger cosmological scales. That is a big question because accounting for five times more of the matter in the universe than everyday matter, dark matter should have played a major role in how the cosmos developed.

To solve this conundrum and to discover if dark matter could be governed by a fifth, thus far unknown fundamental force, researchers from the University of Geneva (UNIGE) set about determining if dark matter falls into cosmic gravity wells on vast scales just as ordinary matter does. These gravity wells are created when bodies of tremendous mass cause the very fabric of space and time, unified as a single four-dimensional entity called "spacetime," to warp (as established by general relativity). The greater the mass of the body, the more extreme the warping of spacetime, the "deeper" the resultant gravity well, and thus the stronger the gravitational influence.

"To answer this question, we compared the velocities of galaxies across the universe with the depth of gravitational wells," Camille Bonvin, team member and UNIGE researcher, said in a statement. "If dark matter is not subject to a fifth force, then galaxies — which are mostly made of dark matter — will fall into these wells like ordinary matter, governed only by gravity.

"On the other hand, if a fifth force acts on dark matter, it will influence the motion of galaxies, which would then fall into the wells differently. By comparing the depth of the wells with the galaxies' velocities, we can therefore test for the presence of such a force."

With this approach and using up-to-date cosmological data, the team established that dark matter does indeed slip into gravity wells just as ordinary matter does. While these findings provide no hints of a fifth fundamental force of nature, they can't absolutely rule it out.

"At this stage, however, these conclusions do not yet rule out the presence of an unknown force. But if such a fifth force exists, it cannot exceed 7% of the strength of gravity — otherwise it would already have appeared in our analyses," Nastassia Grimm, team leader and researcher at the Institute of Cosmology and Gravitation, University of Portsmouth in the UK.

While these results don't close the book on a fifth force of nature governing dark matter, they do help better define the characteristics of this disturbingly elusive form of matter. And if there is a fifth force of nature, it likely won't be able to hide forever.

"Upcoming data from the newest experiments, such as LSST [the Legacy Survey of Space and Time conducted by the Vera C. Rubin Observatory and DESI [the Dark Energy Spectroscopic Instrument], will be sensitive to forces as weak as 2% of gravity," Isaac Tutusaus, team member and researcher at the University of Toulouse, said. "They should therefore allow us to learn even more about the behaviour of dark matter."

The team's research was published on Monday (Nov. 3) in the journal Nature Communications.

From galaxy rotation curves that defy Newton's laws to gravitational lensing that bends light in eerie ways, scientists have been piecing together clues about dark matter like interstellar sleuths.

Particle physicists, astronomers, and cosmologists have built massive underground detectors, launched satellites, and even proposed entire new particles — all in pursuit of this elusive substance.

This quiz will test your knowledge of the strange, shadowy realm of dark matter. We'll explore the history of its discovery, the theories that try to explain it, and the cutting-edge experiments designed to catch it in the act.

Whether you're a seasoned space nerd or just curious about the universe's biggest mystery, you're in for a brain-bending ride.

Try it out below and see how well you score!

An unexpected monster black hole was found hiding inside one of the Milky Way's tiniest neighbors, rewriting what scientists thought they knew about how small galaxies hold themselves together.

Segue 1 is an ultra-faint dwarf galaxy located about 75,000 light-years from Earth, making it a very close neighbor of the Milky Way. Advanced modeling technologies revealed that the galaxy appears to be dominated not by dark matter as long believed, but rather by a central black hole roughly 450,000 times the mass of the sun, according to a statement from the University of Texas McDonald Observatory.

"Our work may revolutionize the modeling of dwarf galaxies or star clusters to include supermassive black holes instead of just dark matter halos," Nathaniel Lujan, a graduate student at the University of Texas at San Antonio and lead author of the study, said in the statement.

Segue 1 is one of the Milky Way’s faintest companions, containing only a few hundred to a few thousand stars — far too few to generate enough gravity to stay intact. Astronomers have long assumed massive dark matter halos provide the gravity needed to keep such small galaxies intact.

However, when researchers modeled the motions of stars within Segue 1, the only simulations that matched observations from the W.M. Keck Observatory were those featuring a heavyweight black hole at the galaxy’s core. The models showed that the stars located near the center were traveling in quick, tight circles, which is a tell-tale sign of an immense gravitational pull generated by a black hole.

"The black hole in Segue 1 is significantly larger than what is expected,” Karl Gebhardt, a professor of astrophysicists at the University of Texas at Austin and co-author of the study, said in the statement. “If this large mass ratio is common among dwarf galaxies, we will have to rewrite how these systems evolve."

The newly discovered black hole outweighs all the galaxy's stars combined by about a factor of ten, which is uncommon among most galaxies in the universe, according to the statement.

Given Segue 1's proximity to the Milky Way, the researchers suggest that the dwarf galaxy may have once been larger, but lost most of its stars over time to the Milky Way’s tidal forces.

Segue 1 could also be a nearby counterpart to a newly discovered class of galaxies called "little red dots" — compact, early galaxies that formed with massive black holes and only a sprinkling of stars. While those distant systems are almost impossible to study directly, Segue 1 offers astronomers a rare chance to examine similar processes unfolding much closer to home.

Either way, the discovery challenges long-standing ideas about how small galaxies form and evolve — and reveals that even the faintest corners of the cosmos can harbor big surprises.

Their findings were published Oct. 14 in the Astrophysical Journal Letters.

Named for the pioneering astrophysicist Vera C. Rubin, whose work confirmed the existence of dark matter, the Vera C. Rubin Observatory stands as one of the most ambitious ground-based telescopes ever built.

Rubin's mission is to survey the entire southern sky every three nights, using its 8.4-meter Simonyi Survey Telescope and a record-breaking 3.2 gigapixel LSST Camera, the largest digital camera.

What is it?

This image captures the Rubin Observatory beneath a dazzling sweep of the southern Milky Way galaxy, with the Large Magellanic Cloud glowing softly to the left. The Milky Way's arc above mirrors the vast field Rubin will soon observe in exquisite detail, night after night, as it builds the most comprehensive record of the changing night sky ever attempted.

Where is it?

The Rubin Observatory is located at the summit of Cerro Pachón in the Chilean Andes mountains.

Why is it amazing?

Now that it's fully operational, Rubin is embarking on a 10-year-long survey, known as the Legacy Survey of Space and Time (LSST), which will record the positions, brightness and motions of billions of celestial objects. The amount of data it will collect is so large that astronomers working at the observatory need an electronic 'data butler' to help manage the telecope's images.

Using its camera, Rubin will detect up to 10 million transient changes in the sky every single night, from asteroids to supernovas.

Want to learn more?

You can learn more about the Vera C. Rubin Observatory and other ground-based telescopes.

The century-old mystery of dark matter — the invisible glue thought to hold galaxies together — just got a modern clue.

Scientists say they may be one step closer to confirming the existence of this elusive material, thanks to new simulations suggesting that a faint glow at the center of the Milky Way could be dark matter's long-sought signature.

"It's very hard to actually prove, but it does seem likely," Moorits Muru of the Leibniz Institute for Astrophysics Potsdam in Germany, who led the new study, told Space.com.

Dark matter, which makes up about 27% of the matter in the universe, remains one of the biggest riddles in cosmology. It doesn't absorb or reflect light, making it completely invisible to telescopes. Despite decades of experiments, from underground particle detectors to orbiting space observatories, scientists have never detected it directly. Now, however, new computer simulations from Muru's team may have brought us a step closer to decoding the mystery.

The findings, show that dark matter near the Milky Way's center might not form a perfect sphere as scientists long thought. Instead, it appears flattened, almost egg-shaped, and that shape closely mirrors the pattern of mysterious gamma rays observed by NASA's Fermi Gamma-ray Space Telescope.

This builds on research dating back to 2008, when Fermi first spotted a broad, hazy glow of high-energy light near the galactic core, stretching across some 7,000 light-years. The signal was far brighter than existing models could explain.

Some scientists proposed that these rays could be the by-product of invisible dark matter particles known as WIMPs (short for weakly interacting massive particles) colliding and annihilating one another. Others argued they came from fast-spinning stellar remnants known as millisecond pulsars — ancient, rapidly spinning neutron stars that emit beams of radiation like cosmic lighthouses.

The pulsar theory made sense because the gamma-ray glow appeared flattened and bulging, much like the Milky Way's star-filled central region. If dark matter were behind the glow, scientists had expected a smoother, rounder pattern.

Muru and his team decided to put both ideas to the test. Using powerful supercomputers, they recreated how the Milky Way formed, including billions of years of violent collisions and mergers with smaller galaxies. Those violent events, the researchers found, left deep "fingerprints" on the way dark matter is distributed in the galactic core.

When this complex history is factored in, the simulated dark matter halo no longer looks spherical. Instead, it takes on a flattened, egg-like form — matching the pattern of gamma-ray emission Fermi has observed, the new study reports.

"We're showing that dark matter also has this flattened shape," Muru said. "So, it does match the [gamma ray] excess much better than expected before."

The finding suggests that dark matter could still be a strong contender behind the Milky Way's mysterious glow. But it doesn't completely rule out pulsars, the researchers say. Both possibilities, the team concludes, are now "essentially indistinguishable."

If the excess truly arises from dark matter collisions, it would mark the first indirect evidence that WIMPs, a leading dark matter candidate, really exist.

Definitive answers could come by the late 2020s, when the Cherenkov Telescope Array Observatory (CTAO) begins scanning the skies from its twin sites in Chile and Spain. The facility will be able to observe gamma rays at much higher resolution than Fermi, researchers say, potentially helping them distinguish between a swarm of pulsars, which have higher energies, and lower-energy annihilating dark matter particles.

Muru added that gamma-ray observations of smaller dwarf galaxies orbiting the Milky Way, whose cores also host dark matter in dense pockets, could further test both possibilities.

"That's where we hope to measure the signal," said Muru. "We're really looking forward to these observations."

Scientists are convinced dark matter is out there. The quest to detect it arguably remains both one of the most frustrating and most exhilarating challenges in modern physics.

"For some reason, it still eludes us," Muru said. "And I think the mystery makes it even more interesting."

The results were detailed in a paper published Oct. 16 in the journal Physical Review Letters.

Astronomers have unveiled a new catalog of massive galaxy clusters, revealing insight on the evolution of the universe.

Galaxy clusters — the largest gravitationally bound structures in the universe — act as cosmic signposts that trace the distribution of dark matter and the mysterious dark energy driving the universe's accelerated expansion. Each containing hundreds to thousands of galaxies, these clusters' characteristics such as size depend on how cosmic structures form and evolve. Thus, they're a powerful test of cosmological models.

The new catalog of galaxy clusters was assembled using six years of data collected by the Dark Energy Survey (DES). The project leveraged a powerful Dark Energy Camera (DECam) mounted to the 4-meter Blanco Telescope in Chile to provide one of the most detailed looks yet at how matter clumps together across cosmic time, according to a statement from the University of Chicago.

Observations from the DES revealed tens of thousands of clusters spanning billions of light-years, giving scientists a vast dataset to measure how structure grows. The DES team used optical and near-infrared observations from the DECam to detect faint galaxies and estimate their distances, building a 3D picture of the cosmic web.

One of the main goals was to see whether the universe today behaves as predicted by the leading cosmological model, known as Lambda-Cold Dark Matter (LCDM). For years, scientists have debated a mild mismatch — the so-called "S8 tension" — between how strongly matter appears to clump in the present-day universe versus how it should based on early-universe data from the cosmic microwave background.

"Our results find that the Lambda-CDM model describes the observable universe well," Chun-Hao To, lead author of the study from the University of UChicago, said in the statement.

Because dark matter and dark energy cannot be observed directly, scientists use massive clusters to better understand these mysterious forces, which are known to push galaxies together or apart. And because clusters are so massive, it's easier to see the effects of dark matter and dark energy on them than it would be on smaller objects, the researchers said.

Creating the new catalog required careful modeling of how clusters overlap and how their masses are estimated. Future telescopes like the Vera C. Rubin Observatory and NASA’s Nancy Grace Roman Space Telescope will probe much deeper. As those observatories come online, astronomers expect to expand the catalog dramatically, tracking how clusters formed across more of the universe’s history.

For now, the new DES galaxy cluster catalog offers one of the clearest maps yet of the cosmic landscape. Their findings were published Sept. 18 in the journal Physical Review D.

Dark matter, one of the universe's best kept secrets, may have been quietly painting the cosmos in faint, detectable hues of red and blue all along, a new study suggests.

Dark matter makes up more than 80% of the matter in the universe, yet it doesn't emit, absorb, or reflect light, making it impossible to observe directly. Now, a new theoretical study by scientists at the University of York in the U.K. suggests light passing through dark-matter-rich regions of space could pick up a faint tint — slightly red or blue, depending on the kind of dark matter it encounters.

The effect would be extraordinarily subtle, far too weak for current telescopes to detect, but potentially measurable with the next generation of ultra-sensitive observatories, the researchers say.

"It's a fairly unusual question to ask in the scientific world, because most researchers would agree that dark matter is dark," study co-author Mikhail Bashkanov of the University of York said in a statement. "But we have shown that even dark matter that is the darkest kind imaginable — it could still have a kind of colour signature."

The team likens the concept to the "six handshakes rule," the 20th-century theory that any two people on Earth are connected by a chain of, at most, six acquaintances. In a similar way, the study suggests, even if dark matter doesn't interact directly with light, it might do so indirectly through intermediate particles that both sides "know," including the Higgs boson, the so-called "God particle" that represents the Higgs field, which is responsible for giving other particles their mass.

This indirect link could allow photons, the particles of light, to scatter ever so slightly off dark-matter particles, leaving behind a whisper of color or polarization "fingerprint" in the light, the study suggests.

"It's a fascinating idea, and what is even more exciting is that, under certain conditions, this 'colour' might actually be detectable," Bashkanov said in the statement. "With the right kind of next-generation telescopes, we could measure it."

In their study, published earlier this month in the journal Physics Letters B, Bashkanov and his team carried out what they say are the first detailed calculations of how strongly light could scatter off dark matter.

The findings suggest that if dark matter is made up of Weakly Interacting Massive Particles, or WIMPs, which interact through the weak nuclear force, then light passing through a WIMP-rich region would lose some of its high-energy blue photons first, leaving the transmitted light slightly red-tinted. In contrast, if dark matter interacts only through gravity, photons would scatter in the opposite way, giving the light a faint blue shift, the study notes.

In both situations, the interactions are minute but not zero, researchers say, meaning dark matter could leave behind a detectable "fingerprint" on light that travels through dense regions of it, such as the centers of galaxies or galaxy clusters.

Their calculations show that these effects could slightly distort the light spectrum of distant objects. A galaxy's glow, for instance, might appear microscopically redder or bluer depending on the dominant type of dark matter lying between it and Earth. In principle, such differences could help scientists distinguish between dark-matter models based on whether cosmic light skews red or blue as it travels through dark-matter-rich space.

"Right now, scientists are spending billions building different experiments — some to find WIMPs, others to look for axions or dark photons," Bashkanov said in the same statement. "Our results show we can narrow down where and how we should look in the sky, potentially saving time and helping to focus those efforts."

Detecting such tiny shifts would require ultra-precise telescopes and painstaking analysis of light that has traveled billions of light-years across the cosmos. Future observatories with exceptional spectral and polarization sensitivity, such as the European Extremely Large Telescope and NASA's Nancy Grace Roman Space Telescope, could one day test these predictions.

If confirmed, the findings would open an entirely new observational window on dark matter, bringing scientists a step closer to unraveling one of the greatest mysteries in cosmology.

A "dark object" detected as an anomalous notch in the arc of a gravitationally warped section of space, could be the smallest clump of pure dark matter yet found.

If so, it would further validate the concept of cold dark matter and will help constrain the properties of dark matter particles as physicists and astronomers continue to hunt for what exactly the invisible substance is made from.

"Hunting for dark objects that do not seem to emit any light is clearly challenging," said Devon Powell of the Max Planck Institute for Astrophysics in Germany in a statement.

The discovery came as a byproduct while scientists were observing an Einstein ring. This is the most spectacular form of gravitational lensing in which the gravity of a foreground object — in this case a massive elliptical galaxy — is warping space. The light from a background galaxy, almost perfectly aligned with the elliptical galaxy and our line of sight, is lensed into an almost complete ring around the foreground galaxy.

Combining the power of radio telescopes across the world, including the European Very Long Baseline Interferometric Network of radio telescopes in Europe, Asia, South Africa and Puerto Rico, plus the Green Bank Telescope in West Virginia in the U.S. and the Very Long Baseline Array in Hawaii, gave astronomers an instrument with a baseline almost as large as Earth.

The larger the baseline, the smaller the details that can be seen.

Astronomers led by John McKean of the University of Groningen, the University of Pretoria and the South African Radio Astronomy Observatory, and Devon Powell of the Max Planck Institute for Astrophysics in Germany, were aiming to resolve the lensed image of a compact symmetric object (CSO). This is an object, such as an active supermassive black hole, that is producing relatively small (smaller than 3,200 light-years) lobes of radio emission.

The team succeeded in identifying the CSO, but in doing so spotted something even more tantalizing. The data had to be analyzed with algorithms running on supercomputers that can produce a "gravitational image," which in essence maps where the gravity is. Close inspection of the gravitational image turned up something surprising: a notch in the arc of radio emission belonging to the CSO and its host galaxy. This notch can only be produced by another object between the background and foreground galaxies and with a mass a million times greater than our sun.

There are two explanations. One is that it is an inactive dwarf galaxy while the other, given that the object seems completely dark, is that it is a relatively small clump of dark matter: the smallest ever seen on its own, by a factor of 100, that's located 10 billion light-years away from us.

"Given the sensitivity of our data, we were expecting to find at least one dark object, so our discovery is consistent with the so-called cold dark matter theory on which much of our understanding of how galaxies form is based," Powell said. "Having found one, the question now is whether we can find more and whether the numbers will agree with the models."

Cold dark matter is the leading model of dark matter, which posits that it is made from low energy particles that can clump together through their mutual gravity. If dark matter were "hot," meaning high in energy, then it wouldn't be able to clump because all its particles would be speeding through space at almost the speed of light, like neutrinos do.

The question has always been, how small can clumps of cold dark matter become? And can small dark matter clumps exist without forming stars inside them? The size of the smallest dark matter clumps can therefore place constraints on the properties of dark matter particles.

"Finding low-mass objects such as this one is critical for learning about the nature of dark matter," said team-member Chris Fassnacht of the University of California, Davis.

The findings are described in two papers, one in Nature Astronomy discussing the dark object, and one in Monthly Notices of the Royal Astronomical Society focusing on the CSO.

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

For more than a century, physics has been built on two great theories. Einstein's general relativity explains gravity as the bending of space and time.

Quantum mechanics governs the world of particles and fields. Both work brilliantly in their own domains. But put them together and contradictions appear – especially when it comes to black holes, dark matter, dark energy and the origins of the cosmos.

My colleagues and I have been exploring a new way to bridge that divide. The idea is to treat information – not matter, not energy, not even spacetime itself – as the most fundamental ingredient of reality. We call this framework the quantum memory matrix (QMM).

At its core is a simple but powerful claim: spacetime is not smooth, but discrete – made of tiny "cells", which is what quantum mechanics suggests. Each cell can store a quantum imprint of every interaction, like the passage of a particle or even the influence of a force such as electromagnetism or nuclear interactions, that passes through. Each event leaves behind a tiny change in the local quantum state of the spacetime cell.

In other words, the universe does not just evolve. It remembers.

The story begins with the black hole information paradox. According to relativity, anything that falls into a black hole is gone forever. According to quantum theory, that is impossible. Information cannot be ever destroyed.

QMM offers a way out. As matter falls in, the surrounding spacetime cells record its imprint. When the black hole eventually evaporates, the information is not lost. It has already been written into spacetime's memory.

This mechanism is captured mathematically by what we call the imprint operator, a reversible rule that makes information conservation work out. At first, we applied this to gravity. But then we asked: what about the other forces of nature? It turns out they fit the same picture.

In our models assuming that spacetime cells exist, the strong and weak nuclear forces, which hold atomic nuclei together, also leave traces in spacetime. Later, we extended the framework to electromagnetism (although this paper is currently being peer reviewed). Even a simple electric field changes the memory state of spacetime cells.

Explaining dark matter and dark energy

That led us to a broader principle that we call the geometry-information duality. In this view, the shape of spacetime is influenced not just by mass and energy, as Einstein taught us, but also by how quantum information is distributed, especially through entanglement. Entanglement is a quantum feature in which two particles, for example, can be spookily connected, meaning that if you change the state of one, you automatically and immediately also change the other – even if it's light years away.

This shift in perspective has dramatic consequences. In one study, currently under peer review, we found that clumps of imprints behave just like dark matter, an unknown substance that makes up most of the matter in the universe. They cluster under gravity and explain the motion of galaxies – which appear to orbit at unexpectedly high speeds – without needing any exotic new particles.

In another, we showed how dark energy might emerge too. When spacetime cells are saturated, they cannot record new, independent information. Instead, they contribute to a residual energy of spacetime. Interestingly, this leftover contribution has the same mathematical form as the "cosmological constant", or dark energy, which is making the universe expand at an accelerated rate.

Its size matches the observed dark energy that drives cosmic acceleration. Together, these results suggest that dark matter and dark energy may be two sides of the same informational coin.

A cyclic universe?

But if spacetime has finite memory, what happens when it fills up? Our latest cosmological paper, accepted for publication in The Journal of Cosmology and Astroparticle Physics, points to a cyclic universe – being born and dying over and over. Each cycle of expansion and contraction deposits more entropy – a measure of disorder – into the ledger. When the bound is reached, the universe “bounces” into a new cycle.

Reaching the bound means spacetime's information capacity (entropy) is maxed out. At that point, contraction cannot continue smoothly. The equations show that instead of collapsing to a singularity, the stored entropy drives a reversal, leading to a new phase of expansion. This is what we describe as a "bounce".

By comparing the model to observational data, we estimate that the universe has already gone through three or four cycles of expansion and contraction, with fewer than ten remaining. After the remaining cycles are completed, the informational capacity of spacetime would be fully saturated. At that point, no further bounces occur. Instead, the universe would enter a final phase of slowing expansion.

That makes the true "informational age" of the cosmos about 62 billion years, not just the 13.8 billion years of our current expansion.

So far, this might sound purely theoretical. But we have already tested parts of QMM on today's quantum computers. We treated qubits, the basic units of quantum computers, as tiny spacetime cells. Using imprint and retrieval protocols based on the QMM equations, we recovered the original quantum states with over 90% accuracy.

This showed us two things. First, that the imprint operator works on real quantum systems. Second, it has practical benefits. By combining imprinting with conventional error-correction codes, we significantly reduced logical errors. That means QMM might not only explain the cosmos, but also help us build better quantum computers.

QMM reframes the universe as both a cosmic memory bank and a quantum computer. Every event, every force, every particle leaves an imprint that shapes the evolution of the cosmos. It ties together some of the deepest puzzles in physics, from the information paradox to dark matter and dark energy, from cosmic cycles to the arrow of time.

And it does so in a way that can already be simulated and tested in the lab. Whether QMM proves to be the final word or a stepping stone, it opens a startling possibility: the universe may not only be geometry and energy. It is also memory. And in that memory, every moment of cosmic history may still be written.

Peering into deep space, NASA's James Webb Space Telescope has helped astronomers find places to study gravitational lensing, an effect in which massive objects such as galaxies warp space-time itself, bending and distorting the light of even more distant galaxies behind them. Each distorted arc, ring or multiplied galaxy image acts as a natural cosmic magnifying glass, offering astronomers a powerful tool to look further back into the universe's history.

What is it?

These eight images were drawn from the COSMOS-Web program, designed to study galaxy formation across cosmic time. One of the program's goals is to uncover gravitational lenses, and researchers launched the COSMOS-WEB Lens Survey (COWLS) to do just that.

By inspecting over 42,000 lensing candidates by eye, the researchers identified more than 400 promising ones. This collage shows the eight most spectacular examples.

Where is it?

These images were taken across deep space.

Why is it amazing?

Gravitational lensing was first predicted by Albert Einstein in his theory of general relativity. According to Einstein, massive objects shape the space around them, as their gravity bends space-time, curving paths of light rays near by.

When a massive galaxy or galaxy cluster happens to align with a more distant galaxy behind it, the background galaxy's light is deflected on its way to Earth. Depending on the geometry, this can stretch the background galaxy in arcs, duplicate it into multiple images or form near-perfect circles called Einstein rings.

Some of the galaxies shown in this collage were already captured by the Hubble Space Telescope, but the James Webb Space Telescope shows them in greater detail, uncovering new clues about gravitational lensing.

Want to learn more?

You can read more about the James Webb Space Telescope and the theory of general relativity.

Are we living in a simulation? Well, the jury's out on that one. But humans do create simulations all the time.

In fact, the Euclid Consortium, the international group managing the European Space Agency's Euclid space telescope, just published the world's most extensive simulation of the universe. It maps an astonishing 3.4 billion galaxies and tracks the gravitational interactions of more than 4 trillion particles.

Called Flagship 2, the simulation draws from an algorithm designed by astrophysicist Joachim Stadel of the University of Zurich (UZH). In 2019, Stadel used the supercomputer Piz Daint — then the third most powerful supercomputer in the world — to run the calculation, ultimately creating an exceptionally detailed virtual model of the universe.

"These simulations are crucial for preparing the analysis of Euclid’s data," astrophysicist Julian Adamek of UZH, a collaborator on the project, said in a statement.

Since 2023, the Euclid space telescope has been mapping billions of galaxies across the universe, studying the distribution of dark energy and dark matter. The spacecraft will eventually scan about one-third of the night sky. Given the scale of the project, Euclid produces vast quantities of data — and simulations like Flagship 2 help speed up processing times.

While the team anticipates that Euclid's observations will closely match predictions from the simulation, there are likely surprises in store. Flagship 2 runs on the standard cosmological model, which is what we currently know about the universe's composition. But missions like Euclid are designed to challenge our current knowledge. "We already see indications of cracks in the standard model," Stadel said.

The team is particularly excited to study the mystery of dark energy, the force driving the expansion of the universe. As it stands in the standard cosmological model, dark energy is simply a constant. But Euclid's observations — which will look up to 10 billion years in the past — might reveal different characteristics. "We can see how the universe expanded at that time and measure whether this constant really remained constant," said Adamek.

Euclid's first observational data was released in March 2025, with the next publication of data sets scheduled for spring 2026.

Astronomers have discovered a rare cosmic alignment that reveals hidden dark matter, offering a new way to study the invisible substance that makes up most of the universe.

Data from the Northern Extended Millimeter Array (NOEMA) in the French Alps revealed an extra image in the center of what is known as an Einstein Cross — a gravitational lensing effect that causes light from a distant object to bend and appear as four distinct images arranged in a cross-like pattern. In recent observations, the light from a distant, dusty galaxy called HerS-3 was split into five rather than four images, suggesting something unusual was bending the light in this unexpected way, according to a statement from Rutgers University.

An Einstein Cross forms when the gravity of galaxies in the foreground bends and splits the light of a more distant galaxy into four distinct images. However, what puzzled astronomers with regard to the newly studied Einstein Cross this time was a curious fifth image sitting at the center of the cross.

At first, they suspected a data glitch, but the anomaly persisted in repeat observations, including data from the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. The fifth image could not be explained by the visible foreground galaxies alone. Only after adding a massive, invisible halo of dark matter to their computer models could the researchers reproduce what the radio telescope had observed.

"We tried every reasonable configuration using just the visible galaxies, and none of them worked," Charles Keeton, co-author of the study and a professor at Rutgers, said in the statement. "The only way to make the math and the physics line up was to add a dark matter halo. That’s the power of modeling. It helps reveal what you can't see."

Dark matter cannot be seen directly, but its gravitational effects are evident throughout the cosmos. In this case, it not only created the rare lensing pattern but also magnified HerS-3, allowing astronomers to study the distant galaxy in greater detail and the effects of dark matter.

"This system is like a natural laboratory," Pierre Cox, lead author of the study and research director at the French National Centre for Scientific Research, said in the statement. "We can study both the distant galaxy and the invisible matter that’s bending its light."

The team's models suggest future observations could reveal additional features, such as gas flowing out of the galaxy, which would provide further evidence that dark matter is magnifying the details of HerS-3.

Their findings were published on Sept. 16 in The Astrophysical Journal.

New research suggests that there is a 90% chance that within the next decade, humanity could use a space or Earth-based telescope to spot an exploding black hole. Such a detection would change our perspective of the universe by proving the existence of "primordial black holes" born 13.8 billion years ago, a second after the Big Bang.

Scientists have long suspected that black holes can explode, but that the length of time this takes increases in step with the mass of any black hole. Previous estimates have suggested that the largest possible black holes would take longer than the hypothesized lifetime of the universe to explode. Such an explosion would happen to the smallest possible black holes, at most, once every 100,000 years, according to previous theories.

However, the team behind this new study put forward a new model of the electric charge of black holes, which they call a "dark-QED toy model." This model includes a very heavy, hypothesized version of the electron, which the team has dubbed a "dark electron." If that model is correct, then a primordial black hole explosion could be witnessed once every 10 years.

An explosion of a primordial black hole is theorized to flood the universe with all possible particles. That would include the established particles of the standard model of particle physics, electrons, quarks, and Higgs Bosons, as well as the particles beyond the standard model, such as the particles that could make up dark matter.

That means spotting such an explosion could not only reveal the existence of primordial black holes, but it could also solve a wealth of puzzles regarding particles beyond the standard model.

"We're not claiming that it's absolutely going to happen this decade, but there could be a 90% chance that it does," team member Michael Baker of the University of Massachusetts, Amherst, said in a statement. "Since we already have the technology to observe these explosions, we should be ready."

Do black holes 'leak'?

Black holes come in a range of masses, and that fact is integral to the team's theory.

Perhaps the most familiar concept of black holes is the so-called stellar mass black hole, with masses between 10 and 1,000 times the mass of the sun. These black holes are born when massive stars reach the end of their nuclear fuel and can no longer support themselves against their own inward gravitational pull. This results in a region of spacetime with a gravitational influence so great that not even light is fast enough to escape it (putting the "black" in black holes).

With masses equivalent to millions or even billions of suns, supermassive black holes are too massive to have been born from dying stars; instead, it is theorized that they are created when smaller black holes collide and merge, and a chain of progressively larger and larger mergers.

Primordial black holes, meanwhile, are theorized to be much more diminutive than even stellar mass black holes, with masses predicted to be anywhere from that of giant planets down to average-sized asteroids. Primordial black holes are theorized to have been created not from stars but as a result of initial density fluctuations in the universe moments after the Big Bang.

The concept of exploding black holes originated in 1974 when Stephen Hawking, the British physicist and science communicator, suggested that black holes "leak" a type of thermal radiation that would later be dubbed "Hawking radiation."

The emission of Hawking radiation would cause the black hole to gradually evaporate, with this process ending with an explosion. The temperature of this radiation depends on the mass of the black hole emitting it, but this is an inverse relationship; the bigger the black hole mass, the lower the "Hawking temperature." That would also mean that smaller black holes are much hotter than the space around them, meaning they radiate Hawking radiation much more rapidly, losing their already smaller mass more quickly than monstrously massive black holes.

And this is how scientists say we should be able to spot them. "The lighter a black hole is, the hotter it should be and the more particles it will emit. As primordial black holes evaporate, they become ever lighter, and so hotter, emitting even more radiation in a runaway process until explosion," team member and UMass Amherst researcher Andrae Thamm said. "It's that Hawking radiation that our telescopes can detect."

Therefore, astronomers should be able to detect primordial black holes, but if they exist, they've thus far proved elusive.

"We know how to observe Hawking radiation," team member and UMass Amherst researcher Joaquim Iguaz Juan said. "We can see it with our current crop of telescopes, and because the only black holes that can explode today or in the near future are these primordial black holes, we know that if we see Hawking radiation, we are seeing an exploding primordial black hole."

Previously, the chance of detecting an exploding primordial black hole has been deemed infinitesimally small; however, as Iguaz Juan pointed out, "our job as physicists is to question the received assumptions, to ask better questions and come up with more precise hypotheses."

The team questioned assumptions by reconsidering what is theorized about the electric charge of black holes. Stellar mass black holes are considered to be electrically neutral, and until now, primordial black holes were theorized to be the same.

"We make a different assumption," Baker said. "We show that if a primordial black hole is formed with a small dark electric charge, then the toy model predicts that it should be temporarily stabilized before finally exploding."

That results in a primordial black hole explosion occurring on average once every 10 years rather than once every 100,000 years.

The next step for the team is to get ready to make such a detection and take advantage of what they predict is a 90% chance of a primordial black hole exploding.

"This would be the first-ever direct observation of both Hawking radiation and a PBH. We would also get a definitive record of every particle that makes up everything in the universe," Iguaz Juan said. "It would completely revolutionize physics and help us rewrite the history of the universe."

The team's research was published on Wednesday (Sept. 10) in the journal Physical Review Letters.