Cored Dark Matter halos in the Cosmic Neutrino Background

TL;DR

This paper investigates how interactions between dark matter and cosmic neutrinos can alter galaxy structures, especially in small galaxies, and establishes constraints on their scattering cross section based on these effects.

Contribution

It introduces a novel analysis of dark matter-neutrino interactions affecting galactic cores and provides new constraints on their scattering cross section.

Findings

Neutrino interactions can create cored dark matter profiles in small galaxies.

The scattering cross section is constrained to be less than approximately 10^{-31} cm^2.

The effect is most significant in satellite galaxies of the Milky Way.

Abstract

We study the impact of the interaction between DM and the cosmic neutrino background on the evolution of galactic dark matter halos. The energy transfer from the neutrinos to the dark matter can heat the center of the galaxy and make it cored. This effect is efficient for the small galaxies such as the satellite galaxies of the Milky Way and we can put conservative constraint on the non-relativistic elastic scattering cross section as $\sigma_{\chi\nu}\lesssim 10^{-31} {\rm cm}^2$ for 0.1 keV dark matter and 0.1 eV neutrino.