Supersymmetric dark matter and the extragalactic gamma ray background

Area of Science:

• * Astrophysics
• * Particle Cosmology
• * High-Energy Astronomy

Background:

• * The extragalactic gamma-ray background (EGB) is a diffuse glow of high-energy photons observed from beyond our galaxy.
• * Previous studies have attributed the EGB to various astrophysical sources, but a definitive origin remains elusive.
• * Unresolved point sources and potential contributions from dark matter annihilation are key areas of investigation.

Purpose of the Study:

• * To identify the primary sources contributing to the EGRET-observed extragalactic gamma-ray background.
• * To investigate the potential role of neutralino dark matter annihilation within cold dark matter halos as a source of the EGB.
• * To constrain the mass of neutralinos by comparing theoretical models with observational data.

Main Methods:

• * Analysis of data from the Energetic Gamma Ray Experiment Telescope (EGRET).
• * Utilization of high-resolution simulations of cosmic structure formation.
• * Calculation of composite spectra from blazar populations and neutralino annihilation.
• * Comparison of model-predicted spectra with EGRET observations to determine best-fit parameters.

Main Results:

• * The EGRET data can be explained by a combination of an unresolved blazar population and neutralino dark matter annihilation.
• * The best-fit analysis yields a neutralino mass (m(chi)) of 515 (+110)(-75) GeV.
• * Systematic uncertainties in the neutralino mass determination are estimated to be around 30%.

Conclusions:

• * Blazars and neutralino dark matter annihilation are significant contributors to the observed extragalactic gamma-ray background.
• * The study provides a constrained estimate for the mass of neutralinos, a leading dark matter candidate.
• * This research highlights the synergy between observational astronomy and theoretical cosmology in probing fundamental physics.