Resolving Dark Matter Subhalos With Future Sub-GeV Gamma-Ray Telescopes

TL;DR

Future sub-GeV gamma-ray telescopes like e-ASTROGAM could effectively distinguish dark matter subhalos from astrophysical sources by resolving their spatial emission, advancing dark matter detection efforts.

Contribution

This study evaluates the potential of next-generation gamma-ray telescopes to resolve dark matter subhalos, focusing on the capabilities of the proposed e-ASTROGAM mission.

Findings

e-ASTROGAM can clarify the nature of Fermi's dark matter subhalo candidates.

Next-generation telescopes offer unprecedented sensitivity to dark matter annihilation signals.

Spatial resolution improvements can differentiate subhalos from point sources.

Abstract

Annihilating dark matter particles in nearby subhalos could generate potentially observable fluxes of gamma rays, unaccompanied by emission at other wavelengths. Furthermore, this gamma-ray emission is expected to be spatially extended, providing us with a powerful way to discriminate dark matter subhalos from other astrophysical gamma-ray sources. Fermi has detected two dark matter subhalo candidates which exhibit a statistically significant degree of spatial extension (3FGL J2212.5+0703 and 3FGL J1924.8-1034). It has been argued that the most likely non-dark matter interpretation of these observations is that they are each in fact multiple nearby point sources, too close to one another on the sky to be individually resolved. In this study, we consider the ability of next generation gamma-ray telescopes to spatially resolve the gamma-ray emission from subhalo candidates, focusing on the proposed e-ASTROGAM mission. We find that such an instrument could significantly clarify the nature of Fermi's dark matter subhalo candidates, and provide an unprecedented level of sensitivity to the presence of annihilating dark matter in nearby subhalos.