This Is the Most Detailed Simulation of the Universe

Visualization of the intensity of shock waves in the cosmic gas (blue) around collapsed dark matter structures (orange/white). Similar to a sonic boom, the gas in these shock waves is accelerated with a jolt when impacting on the cosmic filaments and galaxies.

What would you do if you had access to one of the most powerful high-performance computing systems in the world? A group of astrophysicists have used the Hazel Hen machine, Germany's fastest mainframe computer, to create the most detailed simulation ever of the entire universe from almost the beginning of time.

Called Illustris: The Next Generation, or IllustrisTNG, the simulation models a cube-shaped universe that is actually much smaller than our own. But it follows the formation of millions of galaxies in a representative region of a universe that is almost one billion light-years per side. The scale and detail of the simulation allows astronomers to study how galaxies form, evolve, and grow, as stars are born and live out their lives.

"When we observe galaxies using a telescope, we can only measure certain quantities," team member Shy Genel from the Flatiron Institute's Center for Computational Astrophysics said in a statement. "With the simulation, we can track all the properties for all these galaxies. And not just how the galaxy looks now, but its entire formation history."

Astronomers frequently use computer modeling to generate simulations of things like galaxy formation, dark matter, and stellar evolution. But the team says IllustrisTNG pushes these types of simulations to new limits — in size, resolution, and physical fidelity.

The new simulations are the “most information-packed, universe-scale simulation ever produced,” and it builds on the original Illustris simulation, which measured 350 million light years per side, according to the statement. For the new simulations, a team of astronomers from five institutions used more than 24,000 processors over more than two months and produced more than 500 terabytes of simulation data.

"Analyzing this huge mountain of data will keep us busy for years to come,” principal investigator Volker Springel at the Heidelberg Institute for Theoretical Studies said in the statement, “and it promises many exciting new insights into different astrophysical processes."

Other institutions involved were the Max Planck Institutes for Astronomy and Astrophysics, Harvard University, and the Massachusetts Institute of Technology. The team has produced three papers that have been published in the journal Monthly Notices of the Royal Astronomical Society.

Each simulation in IllustrisTNG evolves a large swath of a mock universe from soon after the Big Bang until the present day and takes into account a wide range of physical processes that drive galaxy formation. The simulations can be used to study a broad range of topics about how the universe — and the galaxies within it — evolved over time.

The astrophysicists involved say the new tool provides key insights into things like how black holes influence the distribution of dark matter, how heavy elements are produced and distributed throughout the cosmos, and where magnetic fields originate.

Springel said the simulations from IllustrisTNG demonstrate a high degree of realism, using “hydrodynamic simulations to produce predictions of how galaxies evolve” and how the so-called “cosmic web” — a network of filaments of dark matter that connect galaxies — changes over time and how they may change in the future.

Since the simulation can also look back in time, by mapping out the histories of these modeled galaxies, astronomers should be able to see what our own Milky Way looked like just as Earth was being formed.

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