Search for Dark Matter Annihilation in Galaxy Groups.

Area of Science:

• Astrophysics
• Particle Physics
• Cosmology

Background:

• Dark matter comprises a significant portion of the universe's mass.
• Annihilation of dark matter particles is a predicted phenomenon that could produce detectable gamma rays.
• Extragalactic galaxy groups are potential sites for dark matter annihilation due to their mass.

Purpose of the Study:

• To search for evidence of dark matter annihilation in extragalactic galaxy groups.
• To constrain properties of dark matter, such as its annihilation cross-section and mass.
• To investigate the implications for the Galactic Center excess anomaly.

Main Methods:

• Utilized 413 weeks of Fermi Pass 8 gamma-ray data.
• Employed galaxy group catalogs and luminosity-based mass estimates.
• Inferred J factors and applied a conservative substructure boost factor model.

Main Results:

• No significant evidence for dark matter annihilation was detected in the studied galaxy groups.
• Excluded thermal relic cross sections for dark matter masses below ~30 GeV in the bb-bar annihilation channel at 95% confidence.
• Derived bounds comparable to those from Milky Way dwarf spheroidal galaxies.

Conclusions:

• The study places constraints on dark matter properties, comparable to existing limits from the Milky Way.
• Results increase tension for, but do not rule out, dark matter interpretations of the Galactic Center excess.
• A catalog of galaxy groups and their inferred properties is provided for future extragalactic dark matter searches.