Astrophysicists Create “Time Machine” Simulations To Observe the Lifecycle of Ancestor Galaxy Cities

Many astrophysical processes take a long time to develop, making their development difficult to examine. A star like our sun, for example, has a lifetime of around 10 billion years, while galaxies develop over billions of years.

Astrophysicists cope with this by examining a variety of objects and comparing them at various phases of evolution. Because of the time it takes for light to get to our telescopes, they can also look at faraway objects to essentially peep back in time. When we gaze at an object that is 10 billion light years distant, we perceive it as it was 10 billion years ago.

According to a recent study published in the journal Nature Astronomy on June 2, 2022, astronomers have constructed simulations that directly replicate the whole life cycle of some of the biggest groupings of galaxies recorded in the distant cosmos 11 billion years ago for the first time.

Cosmological simulations are essential for understanding how the universe came to be the way it is now, but many of them do not match what astronomers see through telescopes. Most are simply statistically constructed to resemble the actual world. Constrained cosmological simulations, on the other hand, are intended to replicate the structures we see in the cosmos. However, the vast majority of extant simulations of this type have only been used for observations in our local universe, i.e., close to Earth, and have never been used for observations in the distant cosmos.

Metin Ata, a Kavli Institute for the Physics and Mathematics of the Universe Project Researcher and first author, and Project Assistant Professor Khee-Gan Lee, a Kavli Institute for the Physics and Mathematics of the Universe Project Assistant Professor, 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 discovered that recent studies of distant protoclusters were frequently oversimplified, implying that they were carried out using basic models rather than simulations.

“We wanted to try developing a full simulation of the real distant universe to see how structures started out and how they ended,” Ata explained.

COSTCO was the end consequence (COnstrained Simulations of The COsmos Field).

Creating the simulation, according to Lee, was similar to building a time machine. The galaxies that telescopes detect now represent a glimpse of the past because light from the distant cosmos is just now reaching Earth.

“It’s like finding an old black-and-white picture of your grandfather and creating a video of his life,” he explained.

In this way, the researchers studied how clusters of galaxies emerge by taking photographs of "young" grandparent galaxies in the cosmos and then fast forwarding their age.

The light from the galaxies utilized by the researchers traveled 11 billion light-years to reach us.

Taking into account the large-scale environment was the most difficult part.

“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,” stated Ata. 

Another reason the researchers conducted these simulations was to put the mainstream cosmological model, which is used to describe the mechanics of the universe, to the test. Researchers might uncover previously unnoticed differences in our present knowledge of the cosmos by forecasting the eventual mass and distribution of objects in a particular location.

The researchers were able to locate evidence of three previously described galaxy protoclusters and disfavor one structure using their models. Furthermore, they were able to discover five additional structures that emerged regularly in their simulations. This includes the Hyperion proto-supercluster, the largest and earliest known proto-supercluster, which has 5000 times the mass of our Milky Way galaxy and will collapse into a huge 300 million light-year filament, according to the researchers.

Their work has already been used to other initiatives, such as studying the cosmic environment of galaxies and distant quasar absorption lines, to mention a few.