Why I Think That Dark Matter Has Large Self-interactions

Abstract

We describe a self-interacting dark matter (SIDM) model that can explain the diverse rotation curves of spiral galaxies while maintaining the success of the cold dark matter model on large scales. The explanation is economical in that it only requires one parameter, the self-interaction cross section, which is common to all galaxies. The existence of this solution is demonstrated through fits to a diverse set of 135 rotation curves from the SPARC sample. Despite the apparent diversity, the model exhibits a tight correlation between the accelerations due to the dark and luminous matter. The inferred stellar mass-to-light ratios, halo masses, and halo concentrations are consistent with independent expectations from astrophysics and cosmology.