Eris galaxy

After nine months of number-crunching on a powerful supercomputer, a beautiful spiral galaxy matching our own Milky Way emerged from a computer simulation of the physics involved in galaxy formation and evolution.

The simulation by researchers at the University of California, Santa Cruz, and the Institute for Theoretical Physics in Zurich solves a longstanding problem that had led some to question the prevailing cosmological model of the universe.

Simulation of Milky WayOn the left is Eris, as shown after 13 billion years. On the right is M74; a spiral galaxy similar to the Milky Way. Both are coloured to show gas clouds in red and stars in blue. Image: University of Zurich & NASA.


“Previous efforts to form a massive disk galaxy like the Milky Way had failed, because the simulated galaxies ended up with huge central bulges compared to the size of the disk,” said Javiera Guedes, who recently earned her Ph.D. in astronomy and astrophysics at UC Santa Cruz and is first author of a paper on the new simulation, called “Eris.” The paper has been accepted for publication in the Astrophysical Journal.

The Eris galaxy is a massive spiral galaxy with a central “bar” of bright stars and other structural properties consistent with galaxies like the Milky Way. Its brightness profile, bulge-to-disk ratio, stellar content, and other key features are all within the range of observations of the Milky Way and other galaxies of the same type. “We dissected the galaxy in many different ways to confirm that it fits with observations,” Guedes said.

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