A Multi-frequency analysis of dark matter annihilation interpretations of recent anti-particle and gamma-ray excesses in cosmic structures

TL;DR

This study evaluates dark matter annihilation models explaining recent gamma-ray and anti-particle excesses, predicting their multi-frequency signatures across cosmic structures and assessing detection prospects with upcoming telescopes.

Contribution

It provides a comprehensive multi-frequency analysis of dark matter models linked to recent cosmic excesses, highlighting their observational constraints and detection prospects with future instruments.

Findings

Multi-frequency data disfavors dark matter explanations for anti-particle excesses in Coma and Draco.

Models fitting galactic center gamma-ray excess are less constrained by multi-frequency observations.

Next-generation telescopes like ASTRO-H can effectively probe neutralino annihilation signatures.

Abstract

The Fermi-LAT observation of a gamma-ray excess from the galactic-centre, as well as the PAMELA, AMS, and AMS-2 anti-particle excesses, and the recent claim of a Fermi-LAT excess in the Reticulum-2 dwarf galaxy have been put forward as signatures compatible with of neutralino dark matter. These are of particular interest as the neutralino annihilation models which fit these observations might have observable consequences from radio to gamma-ray emission. Since dark matter is expected to be a major matter constituent of cosmic structure, these multi-frequency consequences should also be common to structures across the mass spectrum. Thus, in this work we make predictions for the multi-frequency spectra of three well-known sources dominated by dark matter, e.g. the Coma cluster, the galaxy M81, and the Draco dwarf galaxy using models favoured by dark matter interpretations of the aforementioned observations. We pay special attention to the consequences for these models when their cross-sections are renormalised to reproduce the recent gamma-ray excess observed in the Reticulum-2 dwarf galaxy, which throw a dark matter interpretation of this excess into doubt. We find that the multi-frequency data of Coma and Draco disfavour the dark matter interpretation of the AMS, PAMELA and Fermi anti-particle excess. Models derived from Fermi-LAT galactic centre observations present somewhat lesser conflicts. We determine the detection prospects of the Square Kilometre Array, the Cherenkov Telescope Array, as well as the ASTROGAM and ASTRO-H satellites for the studied models. This demonstrates that ASTRO-H is well positioned to probe the X-ray emissions from neutralino annihilation. Thus, multi-frequency observation with the next generation experiments will allow for unprecedented sensitivity to the neutralino parameter space.