Constraints on dark matter self-interaction from velocity distribution function in isolated halos

TL;DR

This study investigates how dark matter self-interactions alter velocity distributions in isolated halos and derives bounds on the self-scattering cross-section using galaxy rotation curves.

Contribution

It provides a systematic simulation-based analysis of self-interacting dark matter effects on velocity profiles and establishes new observational bounds on the self-scattering cross-section.

Findings

Bound on self-scattering cross-section: $\sigma/m \,\leq 2.7$ cm$^2$/g at 95% CL

Self-interactions modify velocity distribution profiles in halos

Additional bounds from low surface brightness galaxies and clusters

Abstract

Self-interactions facilitate inter-particle redistribution of energy within the dense regions of galactic halos, implying modifications in the density and velocity distribution of dark matter. Simulating dark-matter only isolated halos for a wide range of mass and specific self-scattering cross-sections, we make a systematic study of the impact of self-scattering on the velocity distribution profiles. We report a conservative bound on $\sigma/m$ $\leq 2.7 \rm cm^2/gm$ at $95\%$ C.L. from observations of rotation curves in Milky-Way size galaxies. Sub-leading bounds from LSB galaxy and clusters are also presented.