Searching for Dark Matter Annihilation from Milky Way Dwarf Spheroidal Galaxies with Six Years of Fermi-LAT Data

TL;DR

This study analyzes six years of Fermi-LAT gamma-ray data from Milky Way dwarf spheroidal galaxies to search for dark matter annihilation signals, setting stringent upper limits on the annihilation cross section.

Contribution

The paper provides the most robust constraints to date on dark matter annihilation cross sections from gamma-ray observations of multiple dwarf spheroidal galaxies.

Findings

No significant gamma-ray detection from dSphs.

Upper limits below the canonical thermal relic cross section for DM masses under 100 GeV.

Constraints are among the strongest available for dark matter annihilation channels.

Abstract

The dwarf spheroidal satellite galaxies (dSphs) of the Milky Way are some of the most dark matter (DM) dominated objects known. We report on gamma-ray observations of Milky Way dSphs based on 6 years of Fermi Large Area Telescope data processed with the new Pass 8 event-level analysis. None of the dSphs are significantly detected in gamma rays, and we present upper limits on the DM annihilation cross section from a combined analysis of 15 dSphs. These constraints are among the strongest and most robust to date and lie below the canonical thermal relic cross section for DM of mass $\lesssim$ 100 GeV annihilating via quark and $\tau$-lepton channels.