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 ⊙ , 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, σ/m < 9.8 cm 2 / gm at 95 % confidence level. We report significant dependence of the derived bounds on the galactic density distribution models assumed for the analysis.