Indirect Signals of Dark Matter Can Change Depending on Where You Look

TL;DR

This paper explores how indirect signals of dark matter vary with the galactic environment, suggesting signals like gamma rays may be concentrated near galaxy centers due to environment-dependent annihilation processes.

Contribution

It introduces models where dark matter signals depend on the local environment, explaining spatial variations in indirect detection signals such as gamma rays.

Findings

Electromagnetic signals of dark matter may only appear near galaxy centers.

The model can account for the Galactic Center gamma ray excess.

Signals depend on the distribution of ordinary matter and long-range forces.

Abstract

We propose that the nature of indirect signals of dark matter (DM) can depend on the Galactic environment they originate from. We demonstrate this possibility in models where DM annihilates into light mediators whose branching fractions depend on a long range force sourced by ordinary matter. In particular, electromagnetic signals of DM may only arise near the centers of galaxies where the ordinary matter densities, and hence astrophysical background levels, are high. We briefly discuss how our model could explain the Galactic Center gamma ray excess, without leaving much of a trace in baryon-poor environments, like dwarf spheroidal galaxies. Similar spatial dependence of indirect signals can also apply to models featuring metastable DM decay into light mediators.