Constraining Dark Matter Properties with Gamma-Rays from the Galactic Center with Fermi-LAT

TL;DR

This paper evaluates Fermi-LAT's potential to constrain dark matter properties through gamma-ray observations of the galactic center, considering various annihilation channels, astrophysical uncertainties, and background systematics.

Contribution

It introduces a comprehensive analysis including inverse Compton scattering effects and background uncertainties to improve dark matter parameter constraints from gamma-ray data.

Findings

Fermi-LAT can accurately determine dark matter properties below ~200 GeV.

Inverse Compton scattering significantly affects gamma-ray signals for certain annihilation channels.

Systematic background uncertainties impact the precision of dark matter parameter estimation.

Abstract

We study the capabilities of the Fermi-LAT instrument on board of the Fermi mission to constrain particle dark matter properties, as annihilation cross section, mass and branching ratio into dominant annihilation channels, with gamma-ray observations from the galactic center. Besides the prompt gamma-ray flux, we also take into account the contribution from the electrons/positrons produced in dark matter annihilations to the gamma-ray signal via inverse Compton scattering off the interstellar photon background, which turns out to be crucial in the case of dark matter annihilations into mu+mu- and e+e- pairs. We study the signal dependence on different parameters like the region of observation, the density profile, the assumptions for the dark matter model and the uncertainties in the propagation model. We also show the effect of the inclusion of a 20% systematic uncertainty in the gamma-ray background. If Fermi-LAT is able to distinguish a possible dark matter signal from the large gamma-ray background, we show that for dark matter masses below ~200 GeV, Fermi-LAT will likely be able to determine dark matter properties with good accuracy.