Reconstructing Dark Matter Properties via Gamma-Rays with Fermi-LAT

TL;DR

This paper evaluates Fermi-LAT's ability to identify dark matter properties through gamma-ray observations, emphasizing the importance of inverse Compton scattering and analyzing degeneracies between annihilation channels.

Contribution

It introduces a comprehensive analysis including inverse Compton effects and source catalog data to improve dark matter property constraints from gamma-ray signals.

Findings

Potential to constrain dark matter mass below 200 GeV

Inverse Compton flux significantly affects channel identification

Stringent bounds possible with typical thermal cross sections

Abstract

We study the capabilities of the Fermi-LAT instrument for identifying particle Dark Matter properties as mass, annihilation cross section and annihilation channels, with gamma-ray observations from the Galactic Center. For the potential Dark Matter signal, besides the prompt gamma-ray flux produced in Dark Matter annihilations, we also take into account the flux produced by inverse Compton scattering of the electrons and positrons generated in Dark Matter annihilations off the interstellar photon background. We show that the addition of this contribution is crucial in the case of annihilations into e^+ e^- and mu^+ mu^- pairs. In addition to the diffuse galactic and extragalactic background, we also consider the full catalog of high-energy gamma-ray point sources detected by Fermi. The impact of the degeneracies between the different Dark Matter annihilation channels has been studied. We find that for Dark Matter masses below ~200 GeV and for typical thermal annihilation cross sections, it will be possible to obtain stringent bounds on the Dark Matter properties.