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

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.

7 pages, 1 figure, matches published version in PRD; corrected errors in tab. I, added clarification on DM heating of astrophysical objects; main predictions and conclusions are unchanged

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• Cosmologically Varying Kinetic Mixing
• Exploring Ultralight Scalar Assistance in Sterile Neutrino Dark Matter: Cold Spectrum and Unusual X/Gamma-ray Signatures