Astrophysicists have created a ‘time machine’ simulation to observe the life cycle of the ancestors of galactic cities

Many processes in astrophysics take a very long time, which makes it difficult to study their evolution. For example, a star like our sun is about 10 billion years old and galaxies evolve over billions of years.

One way astrophysicists approach this is by looking at different different objects to compare them at different stages of development. They can also look at distant objects to effectively look back, due to the length of time it takes for light to reach our telescopes. For example, if we look at an object 10 billion light years away, we see it as it was 10 billion years ago.

Now, for the first time, researchers have created simulations that recreate the full life cycle of some of the largest groups of galaxies observed in the distant universe 11 billion years ago, according to a new study published June 2, 2022 in the journal. natural astronomy.

Cosmic simulations are essential to studying how the universe came to be the way it is today, but many of them don’t usually match what astronomers observe through telescopes. Most are designed to match the real universe only in a statistical sense. On the other hand, constrained cosmic simulations are designed to reproduce the structures we actually observe in the universe. However, most current simulations of this type have been applied to our local universe, meaning it is close to Earth, but never applied to observations of the distant universe.

A team of researchers, led by the Kavli Institute of Physics and Mathematics of Project Universe researcher and first author Metin Ata and project associate professor Khe-Jan Lee, was interested in distant structures such as massive galaxy clusters, which are the ancestors of today. Galaxy clusters before they coalesce under the influence of their gravity. They found that current studies of distant primordial clusters were sometimes oversimplified, meaning they were conducted using simple models rather than simulations.

Screenshots from the simulation show (top) the distribution of matter corresponding to the distribution of galaxies observed in a light travel time of 11 billion years (when the universe was only 2.76 billion years old or 20% of its current age), and (bottom) the distribution of matter in the same region after 11 billion years. A billion light years or so. Credit: Ata et al.

“We wanted to try to develop a complete simulation of the distant real universe to see how the structures began and how they ended,” Atta said.

Their result was COSTCO (COsmos Constrained Field Simulation).

He told me that developing a simulation is a lot like building a time machine. Since light from the distant universe is only reaching Earth now, the galactic telescopes you spot today are a snapshot of the past.

“It’s like finding an old black and white photo of your grandfather and making a video of his life,” he said.

In this sense, the researchers took snapshots of “young” ancestral galaxies in the universe and then quickly advanced their age to study how galaxy clusters formed.

The light from the galaxies the researchers used traveled 11 billion light-years away to reach us.

The biggest challenge was to take the large-scale environment into account.

“This is a very important thing for the fate of those structures whether they are isolated or related to a larger structure. If you don’t take the environment into account, you will get completely different answers. We have been able to take the large-scale environment into account constantly, because we have a full simulation, and that’s Which is why our prediction is more stable.”

Another important reason why researchers created this simulation is to test the Standard Model of cosmology, which is used to describe the physics of the universe. By predicting the ultimate mass and final distribution of structures in a particular location, researchers can unveil previously undiscovered inconsistencies in our current understanding of the universe.

Using their simulations, the researchers were able to find evidence that three protogalactic groups already exist, and one structure is disturbed. Furthermore, they were able to identify five other structures that are constantly forming in their simulations. This includes the Hyperion proto-supercluster, the largest and oldest proto-supercluster known today that has a mass 5,000 times that of ours.[{” attribute=””>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 June 2.

Reference: “Predicted future fate of COSMOS galaxy protoclusters over 11 Gyr with constrained simulations” by Metin Ata, Khee-Gan Lee, Claudio Dalla Vecchia, Francisco-Shu Kitaura, Olga Cucciati, Brian C. Lemaux, Daichi Kashino and Thomas Müller, 2 June 2022, Nature Astronomy.
DOI: 10.1038/s41550-022-01693-0