For the first time, researchers have created simulations that directly
recreate the full life cycle of some of the largest collections of galaxies
observed in the distant universe 11 billion years ago, reports a new study
in Nature Astronomy.
Cosmological simulations are crucial in determining how the universe became
the shape it is today, but many do not typically match what astronomers
observe through telescopes. Most are designed to match the real universe
only in a statistical sense. Constrained cosmological simulations, on the
other hand, are designed to directly reproduce the structures we actually
observe. However, most existing simulations of this kind have been applied
to our local universe, meaning close to Earth, but never for observations of
the distant universe.
A team of researchers, led by Kavli Institute for the Physics and
Mathematics of the Universe Project Researcher and first author Metin Ata
and Project Assistant Professor Khee-Gan Lee, were interested in distant
structures like massive galaxy protoclusters, which are ancestors of
present-day galaxy clusters before they could clump under their own gravity.
They found current studies of distant protoclusters were sometimes
oversimplified, meaning they were done with simple models and not
simulations.
"We wanted to try developing a full simulation of the real distant universe
to see how structures started out and how they ended," said Ata.
Their result was COSTCO (COnstrained Simulations of The COsmos Field).
Lee said developing the simulation was much like building a time machine.
Because light from the distant universe is only reaching Earth now, the
galaxies that telescopes observe today are a snapshot of the past.
"It's like finding an old black-and-white picture of your grandfather and
creating a video of his life," he said.
In this sense, the researchers took snapshots of "young" grandparent
galaxies in the universe and then fast-forwarded their age to study how
clusters of galaxies would form.
The light from galaxies the researchers used traveled a distance of 11
billion light-years to reach us.
What was most challenging was taking the large scale environment into
account.
"This is something that is very important for the fate of those structures
whether they are isolated or associated with a bigger structure. If you
don't take the environment into account, then you get completely different
answers. We were able to take the large scale environment into account
consistently, because we have a full simulation, and that's why our
prediction is more stable," said Ata.
Another important reason why the researchers created these simulations was
to test the standard model of cosmology, which is used to describe the
physics of the universe. By predicting the final mass and final distribution
of structures in a given space, researchers could unveil previously
undetected discrepancies in our current understanding of the universe.
Using their simulations, the researchers were able to find evidence of three
already published galaxy protoclusters and disfavor one structure. On top of
that, they were able to identify five more structures that consistently
formed in their simulations. This includes the Hyperion proto-supercluster,
the largest and earliest proto-supercluster known today that is 5,000 times
the mass of our Milky Way galaxy, which the researchers found out it will
collapse into a large 300-million-light-year filament.
Their work is already being applied to other projects including those to
study the cosmological environment of galaxies, and absorption lines of
distant quasars to name a few.
Details of their study were published in Nature Astronomy on 2 June.
Reference:
Metin Ata et al, Predicted future fate of COSMOS galaxy protoclusters over
11 Gyr with constrained simulations, Nature Astronomy (2022).
DOI: 10.1038/s41550-022-01693-0
Tags:
Space & Astrophysics