Towards an improved model of self-interacting dark matter haloes

Abstract

We discuss the relation between the strength of the self-interaction ofdark matter particles and the predicted properties of the inner density distributionsof dark matter haloes. We present the results ofN-body simulations for 28 galaxycluster sized haloes performed with the same initial conditions for cold dark matterand for self-interacting dark matter with cross-sections ranging from 0.1 to 10 cm2/g.We provide a simple phenomenological description of these results and compare themto the semi-analytical model typically used in the literature. We find that some of theassumptions made in this model are not satisfied in the simulations. We identify thereasons for this disagreement and improve the semi-analytical model correspondingly.We discuss how simulation results can be properly compared with observations and inparticular how quantities like the core radius and the inner dark matter surface densitydepend on the self-interaction cross-section.