Self-Interacting Dark Matter in Cosmological Simulations

Abstract

Self-Interacting Dark Matter is a cosmologically consistent alternative theory to Cold Dark Matter that solves problems of the Cold Dark Matter model on small scales. Our N-body simulations demonstrate that Self-Interacting Dark Matter creates constant density cores that are consistent with observations of Local Group dwarf galaxies. However, the apparent problems of Cold Dark Matter have natural astrophysical contributions from baryonic supernovae feedback. The evidence for Self-Interacting Dark Matter taken together with the evidence for the need for better feedback models presents a challenging environment in which to place constraints on either. We use high resolution cosmological simulations to compare the detailed properties of galaxies at a range of masses with a focus on dwarf galaxies which are the most dark matter dominated galaxies in the universe. We conclude that it is possible that velocity dependent Self-Interacting Dark Matter could explain the common mass scale of dark matter on small scales, the too big to fail problem, and the core versus cusp problem even in the absence of strong stellar feedback; however, baryonic processes offer solutions to these same problems. We find that once baryon physics and outflows are introduced, cores are created in both Self-Interacting Dark Matter and Cold Dark Matter cosmologies.