Constraints on Dark Matter Annihilation/Decay from the Isotropic Gamma-Ray Background

TL;DR

This paper uses Fermi-LAT gamma-ray background data to set limits on dark matter annihilation and decay, considering both galactic and extragalactic sources, and compares these constraints with other astrophysical observations.

Contribution

It provides new constraints on dark matter models from gamma-ray background data, including the impact of subhalo models and recent cosmic-ray anomalies.

Findings

Most dark matter annihilation/decay channels are disfavored by Fermi-LAT data.

Constraints from IGRB are comparable to dwarf galaxy observations under certain models.

Only dark matter annihilation/decay to mu+ mu- remains viable.

Abstract

In this work we study the constraints on dark matter (DM) annihilation/decay from the Fermi-LAT Isotropic Gamma-Ray Background (IGRB) observation. We consider the contributions from both extragalactic and galactic DM components. For DM annihilation, the evolutions of extragalactic DM halos are taken into account. We find that the IGRB constraints under some DM subhalo models can be comparable to those derived from the observations of dwarf spheroidal galaxies. We also use the IGRB results to constrain the parameter regions accounting for the latest AMS-02 electron-positron anomaly. We find that the majority of DM annihilation/decay channels are strongly disfavored by the latest Fermi-LAT IGRB observation; only DM annihilation/decay to $\mu^+\mu^-$ may be valid.