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Astrophysicists create ‘time machine’ simulations to observe the life cycle of cities in ancient galaxies

Time machine simulations

Scientists are creating “time machine” simulations studying the life cycle of cities in ancestor galaxies.

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

One way for astrophysicists to deal with this is to look at different objects to compare them at different stages of evolution. They can also look at distant objects to effectively look back in time, due to the time it takes for light to travel 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 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 published today. June 2, 2022 in the review natural astronomy.

Cosmological simulations are crucial for studying how the universe got into the shape it is today, but many don’t 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 in the universe. However, most of the existing simulations of this type have been applied to our local universe, that is to say near the 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, looked at distant structures such as massive galaxy protoclusters. , which are the ancestors of the current one. clusters of galaxies before they can clump together under their own gravity. They found that current studies of remote protoclusters were sometimes oversimplified, meaning they were done with simple models and not simulations.

Time machine simulation screenshots

Screenshots from the simulation show (top) the distribution of matter corresponding to the observed distribution of galaxies at a light travel time of 11 billion years (when the Universe was only 2 .76 billion years or 20% of its current age), and (bottom) the distribution of matter in the same region after 11 billion light-years or corresponding to our current time. Credit: Ata et al.

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

Their result was COSTCO (COnstrained Simulations of The COsmos Field).

Lee said developing the simulation was a lot 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 photo 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 rapidly advanced their age to study how galaxy clusters would form.

The light from the galaxies used by the researchers traveled a distance of 11 billion light-years to reach us.

The hardest part was taking into account the large-scale environment.

“It is something that is very important for the fate of these structures, whether they are isolated or associated with a larger structure. If you ignore the environment, you get completely different answers. We were able to account for the large-scale environment consistently because we have a full simulation, and that’s why our prediction is more stable,” Ata said.

Another important reason 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 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 previously published galaxy protoclusters and disfavor one structure. In addition to this, they were able to identify five other structures that regularly formed in their simulations. This includes the Hyperion proto-supercluster, the largest and oldest proto-supercluster known today, which is 5,000 times the mass of our[{” 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

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