Can dark matter annihilation dominate the extragalactic gamma-ray background?

Area of Science:

• Astrophysics
• Particle Physics
• Cosmology

Background:

• Annihilating dark matter (DM) is a proposed source for gamma rays observed from the galactic center and the extragalactic gamma-ray background.
• Understanding the origin of these gamma-ray signals is crucial for particle physics and cosmology.

Purpose of the Study:

• To investigate the likelihood of dark matter annihilation being a primary contributor to the extragalactic gamma-ray background.
• To establish constraints on dark matter properties based on observed gamma-ray fluxes.

Main Methods:

• Utilizing the assumption of universal dark matter halo density profiles.
• Comparing predicted gamma-ray fluxes from DM annihilation with observed fluxes from the galactic center and extragalactic sources.
• Considering the impact of supermassive black holes and baryon cooling on DM density profiles.
• Analyzing the potential influence of dark matter substructure.

Main Results:

• The study indicates it is improbable for dark matter annihilation to be the main source of the extragalactic gamma-ray background without violating observed gamma-ray flux limits from the galactic center.
• Enhancements to dark matter density profiles due to supermassive black holes or baryon cooling strengthen this constraint.
• The presence of substructure could potentially relax these constraints, but requires specific conditions like a large annihilation cross-section and a flat density profile.

Conclusions:

• The findings suggest that dark matter annihilation, under standard assumptions, is unlikely to dominate the extragalactic gamma-ray background.
• Further investigation into dark matter substructure and its properties is warranted to fully understand its potential contribution to gamma-ray signals.