Galactic Signatures of Decaying Dark Matter

TL;DR

This paper develops a general method to constrain decaying dark matter models using Galactic radio and cosmic ray data, accounting for astrophysical uncertainties, and rules out some popular decay scenarios.

Contribution

It introduces a convolution-based framework to derive constraints on any decaying dark matter model from radio and cosmic ray observations, incorporating astrophysical uncertainties.

Findings

Certain dark matter decay models are ruled out under modest assumptions.

The response function approach allows flexible analysis of various decay spectra.

Astrophysical uncertainties significantly influence the derived constraints.

Abstract

If dark matter decays into electrons and positrons, it can affect Galactic radio emissions and the local cosmic ray fluxes. We propose a new, more general analysis of constraints on dark matter. The constraints can be obtained for any decaying dark matter model by convolving the specific dark matter decay spectrum with a response function. We derive this response function from full-sky radio surveys at 408 MHz, 1.42 GHz and 23 GHz, as well as from the positron flux recently reported by PAMELA. We discuss the influence of astrophysical uncertainties on the response function, such as from propagation and from the profiles of the dark matter and the Galactic magnetic field. As an application, we find that some widely used dark matter decay scenarios can be ruled out under modest assumptions.