A new investigation of the structure of galaxy clusters has found it agrees with predictions made by the standard model of cosmology, the best explanation scientists have of the evolution of the universe over its 13.8 billion-year existence.
The research, conducted by a team led by physicists from the SLAC National Accelerator Laboratory at Stanford University, measured X-ray emissions from clusters of galaxies. This helped to reveal the structure of these clusters and the distribution of matter throughout them.
The data they collected conform to a model of universal evolution and structure called the lambda cold dark matter (ΛCDM) model, which suggests that the infant universe was an extremely hot, dense sea of photons and matter tightly coupled as plasma.
Related: No, the Big Bang theory is not 'broken.' Here's how we know.
As the infant universe underwent a period of rapid expansion called inflation, small perturbations spread through the plasma as a sound wave, producing under- and over-densities of both matter and radiation, but not affecting dark matter.
According to the ΛCDM model, the plasma expanded and cooled, and electrons and protons soon combined to form the first atoms, with free electrons no longer infinitely scattering photons. This allowed the universe to become transparent to light. Overdense regions collapsed to birth the first stars, and the universe eventually reached its current state, with clusters of galaxies as the largest bound objects linked by a vast cosmic web of dark matter.
Confirming this ΛCDM model by inferring the mass distributions of galactic clusters from X-ray emissions was no easy task because it's easier to use X-ray emissions as a measurement of mass distribution when the energy of the gas in clusters is balanced by the pull of gravity as it binds the entire system.
This balance is achieved when galaxy clusters have settled down into a "relaxed" state, so mass distribution studies typically focus on these galaxies. That means that when researchers compare real observations with the theoretical predictions of the ΛCDM model, they must take into account that there has been a bias toward selecting these "relaxed" galaxies.
While considering these factors, the team examined computer-simulated clusters produced by The Three Hundred Project, which models galaxy clusters and their environments, assessing what shape the X-ray emission for each cluster should take. To refine their data set, the researchers applied selection criteria that allowed them to identify relaxed clusters in real observations of the universe. Then, they could assess the relationship among the cluster mass, how centrally concentrated this mass was, and the redshift of the clusters.
Redshift is the stretching of the wavelength of light that occurs as a result of the expansion of the universe. The farther light has traveled, the more it is shifted toward the red end of the electromagnetic spectrum. That means the earlier and more distant the galaxy, the more extreme the redshift, thus making this a great measure of both distance and age.
Applying this concept to the simulated Three Hundred Project clusters in addition to 44 real galaxy clusters observed with NASA's Chandra X-ray Observatory, the team found that over the universe's 13.8 billion-year existence, clusters have become more centrally concentrated. At the same time, at any given epoch of the universe, less massive clusters are more centrally concentrated than more massive ones.
"The measured relationships agree extremely well between observation and theory, providing strong support for the ΛCDM paradigm," Elise Darragh-Ford, a doctoral student in physics at Stanford and co-author of the research, said in a statement.
The team now hopes to expand their investigation by collecting more observations from real galaxy clusters. When the Vera C. Rubin Observatory opens its eye on the universe, it will begin the Legacy Survey of Space and Time, which should spot far more galaxy clusters. Joining this quest will be the fourth-generation cosmic microwave background experiment, while the European Space Agency's Athena satellite mission will follow up with more X-ray measurements.
The team's future efforts will also depend on getting more data from simulated galactic clusters. SLAC cosmologists are currently attempting to expand the size of computer simulations of the cosmos while improving accuracy. They will also look at how these observations conform to other cosmological models.
The research is published in the journal Monthly Notices of the Royal Astronomical Society.
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"As the infant universe underwent a period of rapid expansion called inflation, small perturbations spread through the plasma as a sound wave, producing under- and over-densities of both matter and radiation, but not affecting dark matter."
Comments like this seem to have problems now because inflation creates primordial black holes.
Primordial black holes may have 'frozen' the early universe, https://phys.org/news/2023-04-primordial-black-holes-frozen-early.html
Ref - Primordial Black Holes Place the Universe in Stasis, https://arxiv.org/abs/2212.01369, 29-March-2023.
My notes. From the 25-page PDF report cited by phys.org article, "I. INTRODUCTION In a broad class of inflationary scenarios, a population of black holes (BHs) is generated shortly after inflation as a consequence of the gravitational collapse of primordial density fluctuations. Such primordial black holes (PBHs) have received a significant amount of recent attention, in part because they can potentially provide a solution to the dark-matter problem. Indeed, while black holes evaporate over time as a consequence of Hawking radiation , PBHs with masses M ~> 10^15 g would nevertheless have lifetimes longer than the age of the universe. Indeed, a population of PBHs with masses within the range 10^17 g <~ M <~ 10^23 g can potentially account for the entirety of the present-day dark-matter abundance, even when the spectrum of PBHs is approximately monochromatic (for reviews, see, e.g., Refs. ). PBHs with lower masses can also have implications for cosmology. Indeed, PBHs with masses in the range 10^9 g <~ M <~ 10^14 g evaporate at a significant rate during or after Big-Bang nucleosynthesis (BBN), generating energetic particles which can modify the primordial abundances of light nuclei. As a result, the abundance of PBHs with masses in this range is tightly constrained ."
The article doesn't state the redshift that was reached, surprisingly, but it is in the cool illustration caption...
"The newly discovered galaxy GN-z11 is the most distant galaxy discovered so far, at a redshift of 11.1, which corresponds to 400 million years after the Big Bang."
We have seen from the JSWT some greater distances, but this study seems to be an attempt to verify the galaxy formation model using the current BBT. The report is that observing what was emitted as x-rays, I assume, helped allow the astronomers to see those formations, and affirm the modeling.
That is, I assume, just a theory, or two. I doubt technology has come along to confirm these ideas, or am I wrong? They aren't critical to BBT in any way that I'm aware. There is no difference in gravity for the surrounding area when comparing gravity densities. If the Sun were to magically turn into a black hole, it's gravitational influence will not change even a tiny bit. But, if you get really, really close to it, be careful. ;)
Their point about Inflation is simply to help explain how higher density regions allow the formation of galaxies, which is key to the modeling. Because of their focus on galaxy formations, the CMBR gives them what they need. Inflation models aren't needed to explain those anisotropies, only that the anisotropies exist and are measurable.
AFAIK, no BBT model, especially for galaxy formation will ignore DM, it is required in BBT.
Helio you said, "AFAIK, no BBT model, especially for galaxy formation will ignore DM, it is required in BBT."
*it is required in BBT* is not accurate. DM never predicted in BBT even during the days of George Gamow and Ralphe Alpher so DM is not required for BBT. DM is an add on to BBT because of other observations used to claim DM fills our universe, this is just an add on here to BBT now where BBT math becomes flexible to accommodate DM observation claims. BBT does not explain the origin of DM or when DM appears or how much DM appears. The article on PBHs start to define this problem in BBT now in my opinion pointing back to inflation and what happens to different densities assumed in the *early universe* using the new, exotic physics not observed operating in nature today.
Mainstream cosmology incorporates DM. It isn’t trivial and modern BBT includes. Mainstream BBT is the LCDM model, as you’ve already stated, and we both know what the “DM” stands for?
Gamow and Alpher did not know about DM at the time. That began to surface after Vera Rubin’s work in the 60’s, followed by others. Zwicky was first, decades earlier, but the evidence was not solid in favor of one hypothesis over another, especially given ideas to explain-away redshift observations.
BBT is mainstream not for it’s ability to be like a TOE, but for the huge ability to explain the observations we currently see. Recall that theories can only be falsified, and there is no clear objective evidence that does this against BBT. Suppositions and hand-waving by some are like throwing rocks at a tank.
Galileo’s discovery of both crescent and gibbous phases for Venus was powerful and clear evidence against the Aristotle/Ptolemy/Aquinas model that even the Jesuits quickly agreed. Nothing comes close against modern BBT, though it would be nice if it had some real competition. Others tried, but real evidence showed their models were false, so they were shipped off to either Sillyville or Obscurityville.
That is important and why the look back time distances are used and the comoving radial distances in GR expanding space is ignored. In my view, this is a bias in the model.
Helio is correct. DM is not explained concerning its origin or even when DM appears or how much DM appears in BBT, saying that DM is "incorporates DM" into BBT today is the same as what I said, it is an add on to the math and modeling. There is no way to know if DM really fits with BBT because BBT makes no specific predictions for its origin or abundance like BBN part of BBT does for H, He, and perhaps a little Li. As a result, there can never be a falsification it seems. We do not know if BBT created 1 gram of DM before the CMBR formed or what. *Incorporated* is a good description but not something required. Without DM, BBT does not form any structure in the universe just using normal matter. It should be obvious, that the wrong amount of DM emerging in the early universe, like the cosmological constant, can blow the universe up :)
I agree, I looked at Venus with my telescope the other night (13-April-2023) and could see its gibbous shape at 73% illumination and angular size about 15 arcseconds near an 8th magnitude star about 275 light-years away (HIP18833). These changes in Venus are very obvious and visible. BBT is not as good in my opinion as the astronomy of the heliocentric solar system debates even though many apparently believe this. In your post #3, "The article doesn't state the redshift that was reached, surprisingly, but it is in the cool illustration caption..."The newly discovered galaxy GN-z11 is the most distant galaxy discovered so far, at a redshift of 11.1, which corresponds to 400 million years after the Big Bang."
GNz-11 is a good example that is not the same as observing Venus's phase changes or angular size changes. What we observe is the redshift of about 11.1, interpreted look back time distance using GR and SR, about 13.308 Gly. What we do not see, is what this object looks like today at its comoving radial distance from Earth, that is somewhat more than 32 Gly away from Earth today. I do not know what happened to GNz-11 as the universe is assumed to expand for billions of more years after its origin in BBT. GNz-11 sits in space expanding faster than c velocity today (something I do not see), or even if DM is there in it or even if GNz-11 still exists in the universe. That is very different than seeing the phases of Venus which are easily verified.