For the first time, astrophysicists have created a computer simulation of the formation of a spiral galaxy like the Milky Way (above). Researchers at the University of California at Santa Cruz and the Institute for Theoretical Physics in Zurich modeled their galaxy, Eris, using a software platform called Gasoline, which allowed them to track the motion of 60 million particles of gas and dark matter for over 13 billion simulated years. Overall, the simulation required 9 months of number crunching on NASA’s Pleiades supercomputer, with supporting simulations on supercomputers at UCSC and the Swiss National Supercomputing Center.
Previous efforts to model spiral galaxies have failed, ending in disfigured galaxies with central bulges much too large for their disks, according to the researchers. But Eris’ bulge-to-disk ratio, stellar content, and other features fall in line with observations of the Milky Way. The researchers point to a realistic model of star formation as a key to Eris’ success—their high-resolution simulation allowed stars to form only in regions with a high density of particles, resulting in a more accurate distribution of stars. More than just a nice movie, the work supports the cold dark matter theory, which says that the gravitational interactions of dark matter drove the evolution of the universe. A paper detailing the Eris simulation will be published in an upcoming issue of the Astrophysical Journal.