The effect of early dark matter halos on reionization

TL;DR

This paper examines how different dark matter halo properties influence the reionization of the universe, highlighting the potential significance of light dark matter particles in contributing to reionization and cosmic optical depth.

Contribution

It analyzes the impact of dark matter halo profiles, particle masses, and minimum halo masses on reionization, emphasizing the role of light dark matter candidates in this process.

Findings

NFW halos and WIMPs have minimal impact on reionization.

Light dark matter in the MeV range can significantly contribute to reionization.

Halo density profile variations affect the reionization process.

Abstract

The annihilation of dark matter particles releases energy, ionizing some of the gas in the Universe. We investigate the effect of dark matter halos on reionization. We show that the effect depends on the assumed density profile, the particle mass, and the assumed minimum halo mass. For NFW halos and typical WIMPs, we find the effect to be quite small. However, light dark matter candidates in the MeV range can contribute significantly to reionization and can make an important contribution to the measured optical depth. This effect may be used to constrain light dark matter models. We also study the effect of varying the halo density profile on reionization.