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Scientists create a virtual universe

Jenny Winder, News Writer
May 8, 2014, 8:41 UTC

Sen—Astronomers have created a realistic virtual model of the Universe, recreating 13 billion years of cosmic evolution with unprecedented resolution.

The team dedicated five years to developing a computer simulation called Illustris to recreate the Universe as a cube covering 350 million light-years per side. The Illustris simulation includes both normal matter and dark matter using 12 billion 3D pixels.

The actual calculations took three months of "run time", using a total of 8,000 CPUs running in parallel. If the team had used an average desktop computer, the calculations would have required more than 2,000 years to complete.

"Until now, no single simulation was able to reproduce the Universe on both large and small scales simultaneously," said team leader Mark Vogelsberger, of Massachusetts Institute of Technology/Harvard-Smithsonian Center for Astrophysics (MIT/CfA).

He conducted the work, which is reported this week in the journal Nature, in collaboration with researchers at several institutions, including the Heidelberg Institute for Theoretical Studies in Germany.

Still frame from the Illustris simulation centered on the most massive galaxy cluster existing today.

A still frame from the Illustris simulation centered on the most massive galaxy cluster existing today. The blue-purple filaments show the location of dark matter. Bubbles of red, orange and white show where gas is being blasted outward by supernovae or supermassive black holes. Image credit: Illustris Collaboration

Earlier simulations were hampered by lack of computing power and the complexities of the underlying physics. As a result, those programs were either limited in resolution, or forced to focus on a small portion of the Universe. They also had trouble modeling complex feedback from star formation, supernova explosions, and supermassive black holes.

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 cannot use Hubble to follow the evolution of a single galaxy over time.

Hubble eXtreme Deep Field

Hubble eXtreme Deep Field observations divided down the middle: real observation (left side) and mock observation from Illustris (right side). Image credit: Illustris Collaboration

The Illustris simulation was set to begin 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.

"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," said team member Shy Genel of the CfA.

A video shows highights of the Illustris simulation of the Universe. Credit: The Illustris Collaboration

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