We see tons of stars and galaxies twinkling in the universe today, but how much matter is actually there? The question is quite simple, but the answer seems surprising.
This dilemma arises primarily because current cosmological observations disagree regarding the distribution of matter in the universe today.
A new computer simulation that tracks how all the elements of the universe – ordinary matter, dark matter and dark energy – evolve according to the laws of physics would be useful. The stunning image shows the galaxies and clusters of galaxies visible in the image of the Universe being fed by the so-called Cosmic Web. This network is the largest structure in the universe, made of filaments composed of ordinary matter, or baryonic matter, and dark matter.
Unlike previous simulations that only looked at dark matter, this new research, conducted by a project called FLAMINGO (short for Full-Scale Large-Scale Structure Simulation with All-Sky Mapping to Interpret Next Generation Observations), also tracked ordinary matter.
Related: Are we living in a simulation? The problem with this confusing hypothesis.
“Even though dark matter dominates gravity, the contribution of ordinary matter can no longer be ignored,” said Jupp Shaye, a professor at Leiden University in the Netherlands and co-author of three new studies on the Flamingo project, in an article. statement.
As for how much matter the universe actually contains, astronomers say computer simulations like this are not only of cosmic interest but also important investigations to help determine the cause of major differences in cosmology called the “S8 tension.” This is the ongoing debate about how matter is distributed in the universe.
What is S8 tension?
When exploring the universe, astronomers sometimes use the so-called S8 parameter. This parameter essentially describes how “lumpy” or dense all the matter in our universe is, and can be precisely measured using what are known as low-redshift observations. It is used by astronomers Redshift To measure how far away an object is from the ground, and low redshift studies such as “weak gravitational lenses” surveys can shed light on processes occurring in the distant, and therefore older, universe.
However, the value of S8 can also be predicted using a function of the standard form of Cosmology. Scientists can essentially adjust the model to fit the known properties of objects in the cosmic microwave background (CMB), which is the residual radiation from the Big Bang, and calculate the clumping of matter from there.
So, here’s the problem.
The CMB experiment found higher S8 values than weak gravitational lensing surveys. Cosmologists don’t know the reason, and they call this contradiction the S8 tension.
In fact, the S8 tension is an ongoing crisis in cosmology that is not much different from its famous cousin: the Hubble tension, which refers to the contradiction that scientists face in determining the expansion rate of the universe.
The reason why the team’s new simulations don’t provide an answer to the S8’s jitter problem is a big deal, because unlike previous simulations that only took into account the effects of dark matter on the evolving universe, this latest simulation takes into account the effects of dark matter. normal stuff too. Unlike dark matter, this matter is governed by ordinary gravity and the pressure exerted by gas throughout the universe. For example driven by galactic winds Supernova Eruptions and actively accumulating Supermassive black holes This is an important process that redistributes ordinary matter by blowing its particles into space galaxies.
However, studying the new work of ordinary matter as well as some of the more extreme galactic winds is not enough to explain the weak clumping of matter observed in the universe today.
“I’m confused here,” Shay told Space.com. “An interesting possibility is that this tension points to a weakness in the Standard Model of cosmology, or even the Standard Model of physics.”
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2.8 The Gpc box shows the different quantities: gas (bulk temperature and surface density), CDM (dark matter surface density), stars (stellar surface density), and neutrinos (neutrino surface density). All quantities are displayed using a logarithmic color scale to visualize the structure of the dimer.(Image credit: Virgo Flamingo Federation) Gas 2.8 Gpc boxes show different quantities: gas (bulk temperature and surface density), CDM (surface density of dark matter), stars (surface density stars), and neutrinos (surface density of neutrinos). All quantities are displayed using a logarithmic color scale to visualize the dimer structure.(Image credit: Virgo Flamingo Federation) Clean building mechanism 2.8 Gpc boxes show different quantities: gas (bulk temperature and surface density), CDM (dark matter surface density), stars (star surface density), and neutrinos (neutrino surface density). All quantities are displayed using a logarithmic color scale to visualize the dimer structure.(Image credit: Virgo Flamingo Federation) stars 2.8 Gpc boxes show different quantities: gas (bulk temperature and surface density), CDM (surface density of dark matter), stars (surface density stars), and neutrinos (surface density of neutrinos). All quantities are displayed using a logarithmic color scale to visualize the dimer structure.(Image credit: Virgo Flamingo Federation) Neutrinos
Weird physics or flawed models?
So, where does this S8 tension come from?
“We don’t know what makes this so interesting,” Ian McCarthy, a theoretical astrophysicist at Liverpool John Morris University in England and a co-author of three new studies, told Space.com.
But computer simulations, such as those performed by FLAMINGO, can bring us one step closer. This may help reveal the reason for the S8’s jitters as a hypothetical large map of the universe could help identify potential errors in our current measurements. For example, astronomers are slowly ruling out more usual explanations for this problem, such as the fact that it may be caused by general uncertainties in observations of large-scale structures or related to problems in the CMB itself.
In fact, the team estimates that the effects of natural matter may be much stronger than in current simulations. However, this also seems unlikely, as the simulations closely match the observed properties of galaxies and galaxy clusters.
“All of these possibilities are very exciting and have important implications for fundamental physics and cosmology,” McCarthy said. But the most interesting possibility is that “The Standard Model is wrong in some way.”
For example, dark matter may have strange self-interacting properties that are not accounted for in the Standard Model, and S8 jitter could indicate a collapse of our theory of gravity on larger scales, McCarthy said.
However, the latest simulations track the effects of natural matter and subatomic particles known as… Neutrinos – Both have proven important for making accurate predictions about how galaxies have evolved over the centuries – but neither solves the S8 voltage problem.
Here’s the surprising thing: At low redshifts, the universe looks less lumpy than predicted by the Standard Model. But measurements that probe the structure of the universe in between The CMB and low redshift measurements are “completely consistent with standard model predictions,” McCarthy said. “The universe seemed to behave as expected for most of cosmic history, but this changed later in cosmic history.”
Perhaps the key to resolving the S8 tension lies in answering what exactly is driving these changes.
This research is explained inside three Leaves Published in Monthly Notices of the Royal Astronomical Society.
2023-10-25 05:45:33
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