Constraints on dark matter self-interaction from galactic core size

Abstract

Self-interaction of particulate dark matter may help thermalising the central region of the galactic halo and driving core formation. The core radius is expectedly sensitive to the self-interaction strength of dark matter (DM). In this paper we study the feasibility of constraining dark matter self-interaction from the distribution of the core radius in isolated haloes. We perform systematic DM only $N$-body simulations of spherically symmetric isolated galactic haloes in the mass range of $10^{10}$-$10^{15}{M}_{\odot }$, incorporating the impact of isotropic DM self-interaction. Comparing the simulated profiles with the observational data, we provide a conservative upper limit on the self-interaction cross-section, $\sigma /m<$ $9.8$ $\mathrm{c}{\mathrm{m}}^2/\mathrm{gm}$ at $95\%$ confidence level. We report significant dependence of the derived bounds on the galactic density distribution models assumed for the analysis.

Comments: 19 pages, 2 tables and 9 figures, matches published version