Stringent and Robust Constraints on the Dark Matter Annihilation Cross Section From the Region of the Galactic Center

TL;DR

This paper derives new, stringent upper limits on dark matter annihilation cross sections using Fermi Telescope data from the Galactic Center, accounting for various dark matter distribution profiles and astrophysical uncertainties.

Contribution

It provides the first comprehensive analysis showing Galactic Center constraints are comparable or stronger than dwarf galaxy limits under realistic halo profile assumptions.

Findings

Galactic Center constraints are as strong as dwarf galaxy limits for conservative profiles.

For NFW or Einasto profiles, Galactic Center limits are generally more restrictive.

Constraints hold even with large constant-density cores in dark matter distribution.

Abstract

For any realistic halo profile, the Galactic Center is predicted to be the brightest source of gamma-rays from dark matter annihilations. Due in large part to uncertainties associated with the dark matter distribution and astrophysical backgrounds, however, the most commonly applied constraints on the dark matter annihilation cross section have been derived from other regions, such as dwarf spheroidal galaxies. In this article, we study Fermi Gamma-Ray Space Telescope data from the direction of the inner Galaxy and derive stringent upper limits on the dark matter's annihilation cross section. Even for the very conservative case of a dark matter distribution with a significant (~kpc) constant-density core, normalized to the minimum density needed to accommodate rotation curve and microlensing measurements, we find that the Galactic Center constraint is approximately as stringent as those derived from dwarf galaxies (which were derived under the assumption of an NFW distribution). For NFW or Einasto profiles (again, normalized to the minimum allowed density), the Galactic Center constraints are typically stronger than those from dwarfs.