The supermassive black hole sitting at the heart of our galaxy is considered to be a slumbering giant. However, an international X-ray spacecraft has discovered that this wasn't always the case. It turns out this supermassive black hole, Sagittarius A* (Sgr A*), has erupted with powerful and dramatic flares over the course of the last 1,000 years.

This surprising discovery made possible by the joint Japanese-European-American XRISM spacecraft (X-Ray Imaging and Spectroscopy Mission) could change our understanding of how supermassive black holes with masses equivalent to millions or even billions of suns evolve and the role they play in shaping the entire galaxies that swirl around them.

Astronomers are shocked by the finding. "Nothing in my professional training as an X-ray astronomer had prepared me for something like this," team leader Stephen DiKerby of Michigan State University said in a statement. "This is an exciting new capability and a brand-new toolbox for developing these techniques."

All black holes are completely dark because they are bounded by regions called event horizons, a point at which their gravity becomes so strong that not even light can escape their grip. However, matter around black holes can become superheated by the friction created by the immense gravity of these cosmic titans, causing it to glow brightly and throw out powerful flares. Sgr A*, which has a mass equivalent to 4 million suns, isn't known to have produced such emissions, however.

Or at least it wasn't until now.

DiKerby and colleagues discovered the black hole's history of turbulence when they pointed XRISM at a giant cloud of gas known as a molecular cloud near the center of our galaxy, examining the X-rays it emits in painstaking detail. This revealed that the molecular cloud was acting as a cosmic mirror, reflecting X-rays previously emitted by Sgr A* flares.

The sensitivity of XRISM, launched in 2023, allowed the team to measure the energies and shapes of X-ray emissions with groundbreaking precision, revealing the movement of the cloud, and also allowing them to test alternative explanations for the cloud's X-ray glow. This ruled out cosmic rays as a cause of this X-ray echo.

The team's findings also reveal that XRISM is perfectly suited to studying the universe in such fine detail that the joint NASA, Japan Aerospace Exploration Agency (JAXA), and European Space Agency (ESA) mission can uncover the hidden history of the cosmos.

"We're just the lucky scientists who got to solve the problems with handling this data in this brand-new way," DiKerby concluded. "One of my favorite things about being an astronomer is realizing I’m the first human to ever see this part of the sky in this way."

The team's research has been accepted for publication in The Astrophysical Journal Letters.

Supermassive black holes are notoriously messy eaters, but the behemoth at the heart of spiral galaxy NGC 3783 really takes the cake — and then flings it out into space at a fifth the speed of light.

Astronomers recently spotted a gale of hot, charged particles erupting from this black hole in the aftermath of a powerful X-ray flare that occurred just a few hours earlier. As one of the study's co-authors, Matteo Guainazzi,described it in a statement, picture a cosmic storm "similar to the flares that erupt from the sun, but on a scale almost too big to imagine." Guainazzi is a project scientist on the European Space Agency's XRISM X-ray telescope, which led to these results.

And the breathtaking sight could help astrophysicists better understand how supermassive black holes shape the fate of their host galaxies.

Unleashing a Cosmic Storm

Astronomers using XRISM first spotted a brief but intense burst of X-ray radiation erupting from the area around the black hole. A few hours later, XRISM picked up the blast of wind unleashed from the same area racing outward at 134 million miles (216 million kilometers) per hour. XRISM's instruments measured the speed and structure of the wind and pinpointed its source, while instruments on the XMM-Newton X-ray telescope helped measure the extent of the cosmic storm. Space Research Organization Netherlands astrophysicist Liyi Gu, who is another author of the study, and colleagues say the process that spawned the storm is not much different from the process that causes solar flares and coronal mass ejections from our own sun — just on a gargantuan scale.

"The winds around this black hole seem to have been created as the active galactic nucleus’s tangled magnetic field suddenly 'untwisted,'" said Guainazzi.

The magnetic field around our sun is a restless thing. It's constantly in motion, and sometimes its magnetic field lines snap and then reconnect. That violent severing and rejoining kicks off a solar flare, a short burst of radiation from the sun's surface. The same process often flings a massive glob of plasma (electrically-charged gas particles) out into space.

But the supermassive black hole lurking at the core of NGC 3783 is 30 million times the mass of our humble sun, and the magnetic field writhing around is millions of times stronger, so when its lines snap and reconnect, the resulting flare is an eruption of almost unfathomable power.

And, while a typical coronal mass ejection erupts from our sun at more than 3 million miles (4.8 million kilometers) per hour, remember how the blast of wind from NGC 3783's supermassive black hole clocked in at more than 134 million miles per hour. That's about 0.2C, or 20% of the speed of light (just barely fast enough to be considered relativistic, if you're counting).

Supermassive temper tantrums and the fate of galaxies

Supermassive black holes (at least, the ones actively drawing in material from their host galaxies) are known for producing relativistic jets: streams of plasma that blast out in opposite directions from their magnetic poles. Some pairs of relativistic jets can stretch out over more than a million light years, wider than the arms of their host galaxies. These jets can reach speeds much closer to the speed of light and last much longer than this recent one-off burst, but they're powered (in part) by processes similar to what happens in the magnetic field around a supermassive black hole.

Relativistic jets, and just-barely-relativistic flares like this one, aren't the only processes happening around the edges of supermassive black holes. The area of space near a black hole, called the accretion disk, is a region where powerful magnetic field lines dance and where matter gets accelerated to truly ludicrous speeds as it falls inward toward the black hole — and where that speed, and occasional bursts of energy, can fling that matter into space and sometimes out of its host galaxy altogether.

This recently-observed burst of cosmic wind gives astrophysicists a glimpse into the mechanical details of at least one of these processes, and that could help unravel some of the ways in which a supermassive black hole's voracious but often messy eating habits shape the future of its galaxy.

If a black hole pulls in too much material too fast, or if it tosses too much material out of its host galaxy, it can cut off its own food supply and grind star formation in the galaxy to a grinding halt. On the other hand, pushing bursts of plasma back into the galaxy can trigger new waves of star formation. It's a complicated feedback loop, and it’s one physicists want to understand in more detail.

"Windy active galactic nuclei also play a big role in how their host galaxies evolve over time and how they form new stars,” said ESA research fellow Camille Diez, a coauthor of the study, in a recent press release. "Because they’re so influential, knowing more about the magnetism of active galactic nuclei, and how they whip up winds such as these, is key to understanding the history of galaxies throughout the universe."

A paper about this work was published on Dec. 9 in the journal Astronomy and Astrophysics.

Astronomers have used the James Webb Space Telescope (JWST) to observe flares from Sagittarius A*, the supermassive black hole at the heart of the Milky Way, in a new light. The new modelling of these observations could help scientists get to the bottom of how black holes launch these flares, as well as reveal the role magnetic fields play in sculpting matter around these cosmic titans.

The team, including Sebastiano von Fellenberg of the Max Planck Institute for Radio Astronomy in Bonn, Germany, observed flaring from Sagittarius A* (Sgr A*) in the mid-infrared regime for the first time. Flares have been routinely observed in the near infrared regime and in other wavelengths of light before, with each offering a different view of the same flares. That is because all the changes that happen to a black hole flare after its launch and before it fades aren't present in all different wavelengths of light. Thus, observations of a flare in different wavelengths can help better understand the mechanisms black holes use to launch flares and the timescales over which these flares evolve.

Until recently, however, mid-infrared observations have been a missing part of this cosmic jigsaw. Thus, the new James Webb Space Telescope (JWST) observations studied and modeled by the team, first revealed in Jan. 2025, help to bridge the gap in the spectrum of Sgr A* flares between infrared and radio wavelengths: with mid-infrared wavelengths.

"The mid-infrared data is exciting, because, thanks to the new JWST data, we can close the gap between the radio and near infrared regimes, which had been a 'gaping hole' in the spectrum of Sgr A*," von Fellenberg told Space.com. "On the one hand, our mid-infrared flare looks like a typical near-infrared flare, so we now know flares also occur in the mid-infrared regime — and this isn't trivial, as, for instance, the radio variability looks quite different, and we do not see pronounced flare-like peaks in the light curve."

"At the same time," von Fellenberg continued, "the result goes further."

For the first time, he explained, the team was able to observe the source at four different wavelengths simultaneously with a single instrument. This allowed them to measure what's known as the mid-infrared spectral index.

Getting to the bottom of black hole flaring

One of the most famous aspects of black holes is that they are bounded by an outer region called an "event horizon" at which the gravitational influence of a black hole becomes so great that not even light moves fast enough to escape its grip and takes a one-way trip to the singularity at its heart. This means black holes emit no light, or electromagnetic radiation.

To be fair, this may make it seem a little odd to study Sgr A*, a black hole with a mass equivalent to that of over 4 million suns, in any wavelengths of electromagnetic radiation.

However, our galaxy's central supermassive black hole does regularly burp out flares of light. Quite what causes these "burps" isn't yet known, but simulations of supermassive black holes have indicated that it may be the result of interactions between surrounding magnetic fields. When magnetic field lines touch and connect, a vast amount of energy is released and, as a byproduct, this releases a type of radiation called "synchrotron radiation."

The fact that the mid-infrared spectral index of the Sgr A* flare changes over the outburst's lifetime revealed to the team that a phenomenon called "synchrotron cooling" is occurring around Sgr A*. Synchrotron cooling happens when high-speed electrons lose energy by emitting that aforementioned synchrotron radiation. This energy is powering the observed mid-infrared emissions.

"In the absence of high-sensitivity multi-frequency observations, the presence of this expected behavior hadn't been confirmed before," von Fellenberg said. "What is cool about this is that since the speed of this cooling, the cooling time scale, depends on the magnetic field strength, we can now measure it for the given flare."

The researcher explained that though the magnetic field strength had been measurable with near-infrared flares, those measurements didn't allow scientists to measure it independently from other parameters, such as the total number of electrons in the region of the emission.

"This new way of determining the magnetic field strength is particularly useful as it's quite 'clean' in that not a lot of assumptions have to go into the measurement," von Fellenberg continued. "This is very useful for theoretical models, which are poorly constrained in that regard for Sgr A*, because magnetic field strengths are quite important."

The scientists explained that these observations wouldn't have been possible without the JWST, and, in particular, the Medium-Resolution Spectrometer (MRS) operating mode of its Mid-Infrared Instrument (MIRI).

"In order to get such high sensitivity in the mid-infrared, one needs to go to space, as the atmosphere severely messes up ground-based observations at this wavelength," von Fellenberg said. "In addition, the MIRI/MRS instrument is the first instrument to give you such broad wavelength coverage for Sgr A*, a prerequisite to measure the spectral index, so it's really a double whammy!"

The team's research is available on the paper repository site arXiv, with two companion papers also published to the site.

Astronomers have spotted the biggest flare ever seen erupting around a black hole, which also happens to be the most distant flare of this type ever detected.

Discovered using the Zwicky Transient Facility (ZTF), the flare erupted from the supermassive black hole at the heart of an Active Galactic Nucleus (AGN) designated J2245+3743 and located in the center of a galaxy 10 billion light-years away from Earth. AGNs are central regions of galaxies that are dominated by feeding, or "accreting," supermassive black holes.

The supermassive black hole in J2245+3743 is feeding on surrounding gas and dust whirling around it in a flattened cloud shape called an accretion disk, but this flare is actually the result of something else: an unusually massive star venturing too close to the black hole which has a mass 500 million times greater than the sun). The tremendous gravitational influence of the black hole is ripping apart the star, and its stellar remains are being fed to this cosmic titan — an occurrence scientists call a tidal disruption event, or TDE.

"This is unlike any AGN we've ever seen," Matthew Graham, team leader at theCalifornia Institute of Technology (Caltech) and a ZTF scientist, said in a statement. "The energetics show this object is very far away and very bright."

The flare was first spotted in 2018 by the ZTF, with astronomers watching as it brightened by a factor of 40 over the course of a few months. At its peak, the flare was 30 times brighter than any prior black hole flare, emitting as much energy as 10 trillion suns. The previous most powerful TDE was the event nicknamed "Scary Barbie," which comes from its official designation ZTF20abrbeie.

"If you convert our entire sun to energy, using Albert Einstein's famous formula E = mc^2, that's how much energy has been pouring out from this flare since we began observing it," K. E. Saavik Ford, team member and City University of New York (CUNY) Graduate Center researcher, said in the statement.

This black hole flare is continuing to fade, and that indicates to the researchers that it is still swallowing the unfortunate star that ventured too close to it, which is estimated to have had an initial mass of 30 times that of the sun (for comparison, the star being devoured in the Scary Barbie event is thought to have just three to 10 times the mass of the sun).

As Graham colorfully puts it, the ongoing nature of the flare in J2245+3743 is akin to "a fish only halfway down the whale's gullet."

Helping the team continue to study this flare is the fact that the gravity surrounding supermassive black holes is so great that time itself runs slower as you get closer to the outer light-trapping boundary, or "event horizon."

"It's a phenomenon called cosmological time dilation due to the stretching of space and time. As the light travels across expanding space to reach us, its wavelength stretches as does time itself," Graham said. "Seven years here is two years there. We are watching the event play back at quarter speed."

This time dilation effect is exactly why long-term surveys like that conducted by the ZTF are so useful.

The J2245+3743 flare is of scientific interest for another reason. Astronomers have spotted around 100 TDEs thus far, and most haven't occurred in an AGN. This could be because the natural activity of supermassive black holes and the emissions that come from the accretion disk around them can camouflage TDEs. That makes TDEs around already feeding black holes tougher to spot than those involving quiet non-feeding supermassive black holes. But the huge size of J2245+3743 made it more conspicuous than most AGN-based TDEs.

Even so, this black hole flare didn't immediately present itself as something special to the team. It wasn't until 2023, five years after it was initially sighted, that data from the W. M. Keck Observatory in Hawaii revealed the extremely energetic nature of this flare.

At first, it was also important to establish that this extreme object was truly this bright and with energy escaping in all directions, not just directed straight at Earth. The team ruled this possibility out using data from NASA's retired Wide-field Infrared Survey Explorer (WISE).

The team also ruled out a massive supernova explosion as the cause of this flare, thus confirming this to be the brightest black hole flare ever detected and indicating it represents a TDE involving an exceptionally massive star.

"Supernovas are not bright enough to account for this. Stars this massive are rare, but we think stars within the disk of an AGN can grow larger," Ford said. "The matter from the disk is dumped onto stars, causing them to grow in mass."

The discovery of this powerful flare indicates that such events could be occurring across the cosmos, just waiting to be uncovered. The team will continue to go back through ZTF looking for similar events while awaiting data from the Vera C. Rubin Observatory, which could also find usually powerful TDEs.

"We never would have found this rare event in the first place if it weren't for ZTF," Graham concluded. "We've been observing the sky with ZTF for seven years now, so when we see anything flare or change, we can see what it has done in the past and how it will evolve."

The team's research was published on Tuesday (Nov.4) in the journal Nature Astronomy.

Astronomers are dragging the inner workings of black holes out into the light.

The powerful X-ray flares seen erupting from supermassive black holes are tied to the motion of these behemoths' surrounding "coronas," mysterious features that are sources of high-energy light, a new study suggests.

Specifically, supermassive black holes likely flare when their coronas launch away from them, researchers said. [Images: Black Holes of the Universe]

"This is the first time we have been able to link the launching of the corona to a flare," study lead author Dan Wilkins, of Saint Mary's University in Halifax, Canada, said in a statement. "This will help us understand how supermassive black holes power some of the brightest objects in the universe."

No light escapes from black holes themselves, but many of these objects are surrounded by an "accretion disk" of fast-moving, superheated material that emits light in various wavelengths.   

Supermassive black holes lurk at the heart of most (if not all) galaxies, including Earth's own Milky Way. These monsters can contain as much mass as hundreds of millions, or even billions, of suns.

Wilkins and his team studied a supermassive black hole called Markarian 335 (Mrk 335), which is found 324 million light-years away from Earth. In September 2014, NASA's Swift satellite detected a bright flare coming from Mrk 335; the astronomers asked NASA to focus its NuSTAR (Nuclear Spectroscopic Telescope Array) spacecraft on the object to study it further in X-ray light.

Using these various observations, the study team determined that Mrk 335's corona launched away from the black hole at about 20 percent the speed of light, and then eventually collapsed.

"The corona gathered inward at first and then launched upwards like a jet," Wilkins said. "We still don't know how jets in black holes form, but it's an exciting possibility that this black hole's corona was beginning to form the base of a jet before it collapsed."

The new results also suggest that coronas are relatively compact rather than diffuse, as some researchers have posited, study team members said.

"The nature of the energetic source of X-rays we call the corona is mysterious, but now with the ability to see dramatic changes like this, we are getting clues about its size and structure," NuSTAR principal investigator Fiona Harrison, who's based at the California Institute of Technology in Pasadena, said in the same statement.

Harrison is not affiliated with the new study, which was published in the journal Monthly Notices of the Royal Astronomical Society.

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+. Originally published on Space.com.

When the monster back hole at the center of the Milky Way galaxy belched out an exceptionally high number of powerful X-ray flares last year, it made astronomers wonder — is this a sign that the beast chowed down on a passing gas cloud, or is this lack of cosmic etiquette typical for black holes?

The black hole at the center of the Milky Way, known as Sagittarius A* (Sgr A* for short), is typically very quiet – it doesn't eat a lot of material, and there is relatively little light that radiates from the region around it. Which is why the apparent uptick in bright X-ray flares came as a surprise to scientists.

Could the bright flares seen in August 2014 have been caused by a gas cloud that passed too close to the black hole, and become an unsuspecting snack? And if that is the case, what does it tell scientists about what exactly happens to material that falls into a black hole? Alternatively, are these types of flare clusters typical of black holes, and an example of scientists' limited understanding of these mighty beasts? Upcoming observations may shed some light on these dark objects. [Images: Milky Way's Monster Black Hole Shreds … Something]

Bright flare activity increases

Packing a double punch of observational power, NASA's Chandra X-ray Observatory and the European Space Agency's XMM-Newton space telescope have been observing Sgr A* (pronounced "Sagittarius A-star") on and off since 1999. In the last three years, the total coverage time has increased thanks to a series of dedicated observation campaigns.

For long stretches, Chandra's detectors would see only "quiescent" X-ray activity from Sgr A*, and then, suddenly, a bright flare would appear. The center of the Milky Way is one of the most densely populated regions of the galaxy, and the view between Earth and Sgr A* is blocked by stars and gas clouds. The Chandra scientists cherished the light that managed to make its way to their detectors, according to Daryl Haggard, an astrophysicist at McGill University in Montreal,  who studies the black hole using Chandra data.

Haggard is a co-author on a new study suggesting there was a two- to threefold increase in the number of bright flares emitted by Sgr A* beginning in August 2014 and extending through November 2014 (the paper does not show an overall increase in the flare rate). In one particularly active period, five bright X-ray flares burst forth from Sgr A* in a time frame that would typically see only one. One of the flares, seen in September, was three times brighter than any other flare detected from that region. The new paper looked at 15 years of Chandra and XMM-Newton data, as well as data from the SWIFT space telescope, in an effort to show that the increase was not merely a result of greater observation time.

What was happening to cause the increase? According to the new research, there are two leading ideas.

G2, the mystery object

The first hypothesis involves a controversial object called G2. In 2011, a group of astronomers using the Very Large Telescope in Chile announced that this cosmic daredevil was going to make a very tight swing around Sgr A*. What would happen during this close approach was a subject of hot debate, because scientists couldn't say for sure what G2 was – a pure dust cloud or a compact object surrounded by a dust cloud.

If G2 is a solid object, then it should have swung around Sgr A* without being pulled past the event horizon, beyond which nothing, not even light, can escape. But if it is pure gas, scientists predicted that the gravity of the black hole would smear it like a wisp of smoke, and a sizable amount of material would become lunch for Sgr A*. That would, theoretically, produce an increase in the light emitted from the region around the black hole, because when material falls into a black hole it accelerates rapidly, causing it to radiate light.

That means that if G2 is a dust cloud, it could have provided scientists with the first real-time, short-term observation of a black hole eating. To watch one of the most monstrous cosmic creatures in the universe devour a meal right in our own backyard would be an unrivaled opportunity for scientists. It would tell them about how black holes grow over their lifetimes, and provide new insights into the strange physics that takes place near the edge of these extreme gravity wells. Imagine a scientist who is trying to study lions in the wild, but never getting to see them hunt and devour their prey — G2 might finally let scientists watch Sgr A* in action.

The excitement was a palpable lead-up to G2's close approach to Sgr A*. Andrea Ghez, an astrophysicist at the University of California at Los Angeles and one of the scientists who confirmed the existence of Sgr A*, said it was one of the "most watched events in astronomy in my career."

And then, nothing.

Chandra saw nothing, nor did any of the other telescopes observing at the time.

Stefan Gillessen, a researcher at the Max Planck Institute for Extraterrestrial Physics in Germany and one of the lead proponents of the gas cloud theory, argued that G2 might still be a pure gas cloud, but that the dynamics of how and when it would be pulled into Sgr A* were different than originally predicted. Scientists don't fully understand how material might behave around a black hole.

The new suggestion that Sgr A* released an increased number of bright flares in late 2014 could be the missing light show, according to Gabriel Ponti, a research fellow with the Max Planck group and the lead author on the new paper. Perhaps the material from G2 took longer than expected to fall toward the black hole and radiate.

"A year or so ago, we thought [G2] had absolutely no effect on Sgr A*, but our new data raise the possibility that that might not be the case," Ponti said in a statement from Chandra. [Black Holes of the Universe in Images]

A cluster of flares

Ponti cautions that the new research cannot confirm the connection between the flare activity and G2 — there's no evidence to show that it isn't just a coincidence. Plus, the paper points out that observations in infrared light seem to show that G2 has survived its trip around Sgr A*, suggesting it is not a pure gas cloud.

This doesn't rule out the possibility that some of the gas from G2 was pulled into the black hole, but it means scientists would have to have a new model for how much gas could be syphoned from G2. And that raises the question of how quickly material moves through the region around a black hole, and around Sgr A* in particular. Does it flow down to the black hole's gaping maw in a smooth, quickly moving stream, like cream moving through coffee? Or is it slow, like molasses across asphalt? If this burst of flare activity is due to G2 passing by, it would suggest that material falls very quickly, according to Haggard. In fact, it would suggest that material is basically in free- fall as it gets closer to the black hole's event horizon. [The Strangest Black Holes in Space]

The likelihood of a G2 connection to the increased flare activity "seems tenuous to me," Haggard told Space.com. She prefers an alternative possibility — that black holes normally exhibit "flare clustering," or bursts of activity that vary from the "average" behavior they exhibit most of the time.

Ponti writes in his blog post for the Chandra website that other black holes that accrete matter at a similar rate to Sgr A* (but which are millions of times less massive) also show "long-term modulation in their flaring properties." (Another factor to consider is that an object called G1, spotted before G2 and with a similar physical appearance, approached Sgr A* at a similar distance in 2001, but there was "no particular evidence for anything unusual happening as a result of G1's passage." However, he also notes that "the X-ray monitoring was much sparser" at the time.)

Illuminating a black hole

Scientists are still trying to understand why black holes like Sgr A* might release flares in periodic clusters, rather than evenly over time. It could have to do with how the gravitational pull of the black hole destroys matter that falls toward it, perhaps breaking it up into clumps, like a string of pearls that then fall in one after the other, each creating their own flare. It could also have to do with the magnetic properties of the black hole.

The Event Horizon Telescope, a worldwide network of radio telescopes, is currently dedicated to studying the monstrous beast that lives at the heart of Earth's galactic home. No data has come out of the project yet, but the collaboration may provide the best-ever images of a black hole.

"At present, we don't know whether the observed variation has anything to do with G2 or not and we are eager to know what the new data collected in 2015 will tell us," Ponti wrote in a blog post on Harvard University's Chandra website.

The object known as G2 may not have provided a snack for Sgr A*, the way so many people hoped it would. But it is nonetheless a fascinating object, potentially something that astronomers have never seen before. Ghez's group of researchers at UCLA have proposed that it may be two stars that merged into one, and they're wondering if these types of merged stars are typical around Sgr A*, and why.

Sgr A* is the nearest example we have of one of the most captivating creatures in the universe: An object with a gravitational pull so powerful it can bend light, or stop it from ever escaping. There are black holes in the universe that are brighter than entire galaxies, and others that are almost completely invisible. Scientists still aren't sure if falling into a black hole would involve being shredded into long strips like spaghetti, or crushed by all the material that ever fell in before. The flares detected by Chandra and XMM provide clues about what happens to those that enter the cosmic lion's den.

Follow Calla Cofield @callacofield. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.