What the Milky Way's Dwarfs tell us about the Galactic Center extended excess

TL;DR

This paper assesses the consistency of the Galactic Center gamma-ray excess with dark matter annihilation models by jointly analyzing Fermi data from the Galactic Center and dwarf galaxies, considering uncertainties in halo profiles and diffuse emission.

Contribution

It introduces a joint likelihood framework that incorporates halo and diffuse emission uncertainties to test dark matter models against gamma-ray observations from the Galactic Center and dwarf galaxies.

Findings

The preferred dark matter parameters are in tension with dwarf galaxy constraints under certain Milky Way density assumptions.

Higher Milky Way density estimates reduce this tension, making models more consistent.

A specific self-interacting dark matter model remains compatible with both datasets.

Abstract

The Milky Way's Galactic Center harbors a gamma-ray excess that is a candidate signal of annihilating dark matter. Dwarf galaxies remain predominantly dark in their expected commensurate emission. In this work we quantify the degree of consistency between these two observations through a joint likelihood analysis. In doing so we incorporate Milky Way dark matter halo profile uncertainties, as well as an accounting of diffuse gamma-ray emission uncertainties in dark matter annihilation models for the Galactic Center Extended gamma-ray excess (GCE) detected by the Fermi Gamma-Ray Space Telescope. The preferred range of annihilation rates and masses expands when including these unknowns. Even so, using two recent determinations of the Milky Way halo's local density leave the GCE preferred region of single-channel dark matter annihilation models to be in strong tension with annihilation searches in combined dwarf galaxy analyses. A third, higher Milky Way density determination, alleviates this tension. Our joint likelihood analysis allows us to quantify this inconsistency. We provide a set of tools for testing dark matter annihilation models' consistency within this combined dataset. As an example, we test a representative inverse Compton sourced self-interacting dark matter model, which is consistent with both the GCE and dwarfs.