Realistic Simulation of the Formation of a Milky Way-Like Galaxy

The first realistic simulation of a spiral galaxy similar to our own Milky Way has been generated by researchers at the University of California, Santa Cruz, and the Institute for Theoretical Physics in Zurich.

The simulation, called ERIS, took 1.4 million processor hours to complete. And that was on the 7th most powerful supercomputer in the world, NASA’s Pleiades supercomputer, which runs at 1.09 petaflops per second.

The simulation follows the formation of a galaxy equivalent to 7.9 × 10¹¹ solar masses (1 solar mass is equal to the mass of our Sun) and has a total of 18.6 million particles.

The resulting galaxy has a radius of 2.5 kilo-parsecs (about 7.7 × 10¹⁶ kilometers). Previous attempts at simulating a realistic galaxy have failed, resulting in simulated galaxies which have too large of a central bulge. The finding of this study, which has been accepted for publication in Astrophysical Journal, found that,

A high star formation threshold appears therefore key in obtaining realistic late-type galaxies, as it enables the development of an inhomogeneous interstellar medium where star formation and heating by supernovae occur in a clustered fashion. The resulting outflows at high redshifts reduce the baryonic content of galaxies and preferentially remove low angular momentum gas, decreasing the mass of the bulge component.

Another important result of this work is that it supports the idea that cold dark matter constitutes a large portion of the mass in the universe.