Constraints on dark matter annihilations from diffuse gamma-ray emission in the Galaxy

TL;DR

This study uses advanced modeling to constrain dark matter annihilation contributions to the Galaxy's diffuse gamma-ray emission, accounting for astrophysical uncertainties and deriving profile constraints based on gamma-ray data.

Contribution

It introduces a self-consistent modeling approach with the DRAGON code to analyze dark matter effects on gamma-ray emission, considering astrophysical uncertainties and deriving distribution constraints.

Findings

Light ~10 GeV DM strongly constrained in the inner Galaxy.

TeV-scale DM constraints are sensitive to radiation field assumptions.

Method developed to derive DM profile constraints from gamma-ray spectra.

Abstract

Recent advances in gamma-ray cosmic ray, infrared and radio astronomy have allowed us to develop a significantly better understanding of the galactic medium properties in the last few years. In this work using the DRAGON code, that numerically solves the CR propagation equation and calculating gamma-ray emissivities in a 2-dimensional grid enclosing the Galaxy, we study in a self consistent manner models for the galactic diffuse gamma-ray emission. Our models are cross-checked to both the available CR and gamma-ray data. We address the extend to which dark matter annihilations in the Galaxy can contribute to the diffuse gamma-ray flux towards different directions on the sky. Moreover we discuss the impact that astrophysical uncertainties of non DM nature, have on the derived gamma-ray limits. Such uncertainties are related to the diffusion properties on the Galaxy, the interstellar gas and the interstellar radiation field energy densities. Light ~10 GeV dark matter annihilating dominantly to hadrons is more strongly constrained by gamma-ray observations towards the inner parts of the Galaxy and influenced the most by assumptions of the gas distribution; while TeV scale DM annihilating dominantly to leptons has its tightest constraints from observations towards the galactic center avoiding the galactic disk plane, with the main astrophysical uncertainty being the radiation field energy density. In addition, we present a method of deriving constraints on the dark matter distribution profile from the diffuse gamma-ray spectra. These results critically depend on the assumed mass of the dark matter particles and the type of its end annihilation products.