Constraints on a Non-thermal History from Galactic Dark Matter Spikes

TL;DR

This study investigates how galactic dark matter spikes influence indirect detection constraints on non-thermal dark matter, highlighting the potential for improved bounds from gamma-ray observations while emphasizing dependence on early star formation details.

Contribution

It introduces the impact of galactic dark matter spikes on indirect detection constraints, providing new bounds on dark matter annihilation cross sections considering substructure effects.

Findings

Gamma-ray observations can set significant constraints on dark matter models.

Constraints are sensitive to star formation and black hole formation history.

Conservative bounds are possible for WIMPs annihilating to quarks or gauge bosons.

Abstract

In this paper we examine whether indirect detection constraints on dark matter associated with a non-thermal history may be significantly improved when accounting for the presence of galactic substructure in the form of dark matter spikes. We find that significant constraints may be derived from the non-observation of an excess of diffuse gamma-rays and from the properties of bright gamma-ray point sources observed by the Fermi Gamma-Ray Space Telescope, but these constraints depend sensitively on the details of the formation of the first stars and their subsequent black hole remnants. However, we also find that, especially if WIMPs annihilate primarily to quarks or gauge bosons, it is possible to extract meaningful and conservative bounds on the annihilation cross section.