Incredible Simulation of the Universe Created

 Cosmology  

A new computer simulation called Illustris shows the formation of galaxies with unprecedented precision, allowing astrophysicists to indirectly confirm the standard model of cosmology.

Astronomers have created the first realistic virtual universe using a computer simulation called "Illustris." Illustris has recreated 13 billion years of cosmic evolution in a cube 350 million light-years on a side with unprecedented resolution.

"Until now, no single simulation was able to reproduce the universe on both large and small scales simultaneously," says Mark Vogelsberger  of the MIT/Harvard-Smithsonian Center for Astrophysics, who conducted the work in collaboration with researchers at several institutions, including the Heidelberg Institute for Theoretical Studies in Germany.

These results have been published in the journal Nature.

"Illustris is like a time machine. We can go forward and backward in time. We can pause the simulation and zoom into a single galaxy or galaxy cluster to see what's really going on."

Previous simulations of the growth of cosmic structures have broadly reproduced the ‘cosmic web’ of galaxies that we see in the Universe, but failed to create a mixed population of elliptical and spiral galaxies, because of a lack of computing power and the complexities of the underlying physics. Moreover, they were unable to track the small-scale evolution of gas and stars to the present within a representative portion of the Universe. Earlier simulations also had trouble modeling complex feedback from star formation, supernova explosions, and supermassive black holes.

Illustris is a simulation that starts 12 million years after the Big Bang, and traces 13 billion years of cosmic evolution with 12 billion resolution elements in a cube of 106.5 megaparsecs a side. The simulation is filled with a population of elliptical and spiral galaxies, and reproduces the observed distribution of galaxies in clusters and characteristics of hydrogen on large scales, and at the same time matches the ‘metal’ and hydrogen content of galaxies on small scales.

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Illustris employs a sophisticated computer program to recreate the evolution of the universe in high fidelity. It includes both normal matter and dark matter using 12 billion 3-D "pixels," or resolution elements.

The team dedicated five years to developing the Illustris program. The actual calculations took 3 months of "run time," using a total of 8,000 CPUs running in parallel. If they had used an average desktop computer, the calculations would have taken more than 2,000 years to complete.

The computer simulation began a mere 12 million years after the Big Bang. When it reached the present day, astronomers counted more than 41,000 galaxies in the cube of simulated space. Importantly, Illustris yielded a realistic mix of spiral galaxies like the Milky Way and football-shaped elliptical galaxies. It also recreated large-scale structures like galaxy clusters and the bubbles and voids of the cosmic web. On the small scale, it accurately recreated the chemistries of individual galaxies.

Because light travels at a fixed speed, the farther away astronomers look, the farther back in time they can see. A galaxy one billion light-years away is seen as it was a billion years ago. Telescopes like Hubble can give us views of the early universe by looking to greater distances. However, astronomers can't use Hubble to follow the evolution of a single galaxy over time.

"Illustris is like a time machine. We can go forward and backward in time. We can pause the simulation and zoom into a single galaxy or galaxy cluster to see what's really going on," says co-author Shy Genel of the CfA.



SOURCE  Harvard-Smithsonian Center for Astrophysics / Illustris

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