Most of the matter in our universe resides in an unknown component that we refer to as "dark matter." There is six times more mass in dark matter than ordinary matter. For decades it has been assumed that, because there is so much more dark matter than ordinary matter, dark matter must dominate the gravity in our universe, and that wherever the dark matter is, ordinary matter must follow. This assumption led astrophysicists to make predictions for the formation of galaxies that either entirely neglected or poorly modeled the gas and stars in galaxies, according to a press release. In doing so, a number of discrepancies between galaxy formation theory and observations were identified, particularly on "small scales." These discrepancies have evaded solution for so many years that they have become known collectively as the "small scale crisis" of the cold dark matter model for galaxy formation.
In recent years, supercomputers have been used to create some of the most detailed, highest resolution simulated galaxies ever produced, and include the physics of gas and stars. These state-of-the-art simulations are, for the first time, matching many of the observed properties of galaxies, eliminating the discrepancies between theory and observations. In a presentation at the 2015 meeting of the Canadian Astronomical Society/Société Canadienne d'Astronomie (CASCA) in Hamilton, Ontario, Alyson Brooks, from Rutgers, revealed results from simulated galaxies and demonstrates that including the physics of gas and stars can rearrange the dark matter inside of galaxies, revolutionizing our understanding of galaxy formation and leading to new theoretical predictions that can be tested by galaxy observations.
