# The Fermi Galactic Center GeV Excess and Implications for Dark Matter

## TL;DR

This paper analyzes the GeV gamma-ray excess near the Galactic center using Fermi data, exploring uncertainties and implications for dark matter annihilation signals, and sets upper limits on dark matter properties.

## Contribution

It provides a comprehensive uncertainty analysis of the Galactic center gamma-ray excess and discusses its implications for dark matter annihilation signals.

## Key findings

- The Galactic center shows a gamma-ray excess at a few GeV energies.
- Uncertainties in cosmic-ray and gas models affect the excess characterization.
- Control regions also show similar excesses, complicating dark matter interpretations.

## Abstract

The region around the Galactic center (GC) is now well established to be brighter at energies of a few GeV than expected from conventional models of diffuse gamma-ray emission and catalogs of known gamma-ray sources. We study the GeV excess using 6.5 years of data from the Fermi Large Area Telescope. We characterize the uncertainty of the GC excess spectrum and morphology due to uncertainties in cosmic-ray source distributions and propagation, uncertainties in the distribution of interstellar gas in the Milky Way, and uncertainties due to a potential contribution from the Fermi bubbles. We also evaluate uncertainties in the excess properties due to resolved point sources of gamma rays. The Galactic center is of particular interest as it would be expected to have the brightest signal from annihilation of weakly interacting massive dark matter particles. However, control regions along the Galactic plane, where a dark-matter signal is not expected, show excesses of similar amplitude relative to the local background. Based on the magnitude of the systematic uncertainties, we conservatively report upper limits for the annihilation cross section as function of particle mass and annihilation channel.