Cosmic Gamma-ray from Inverse Compton Process in Unstable Dark Matter Scenario

TL;DR

This paper investigates gamma-ray emissions resulting from inverse Compton scattering caused by decay products of unstable dark matter, assessing observational constraints from Fermi data.

Contribution

It provides detailed calculations of galactic and cosmological gamma-ray fluxes from unstable dark matter decay, linking them to cosmic-ray anomalies and gamma-ray observations.

Findings

Galactic gamma-ray fluxes are significant and potentially observable.

Cosmological gamma-ray contributions are non-negligible.

Large dark matter masses over TeV scale may be constrained by Fermi observations.

Abstract

Motivated by the PAMELA anomaly in the fluxes of cosmic-ray positron and electron, we study the cosmic gamma-ray induced by the inverse Compton (IC) scattering process in unstable dark matter scenario assuming that the anomaly is due to the positron and electron emission by the decay of dark matter. We calculate the fluxes of IC-induced gamma-ray produced in our Galaxy and that from cosmological distance, and show that both of them are significant. We discuss a possibility that large dark matter mass over TeV scale might be constrained by the gamma-ray observation by Fermi Gamma-ray Space Telescope.