Radio constraints on dark matter annihilation in the galactic halo and its substructures

TL;DR

This paper uses radio observations of the galactic halo and substructures to set constraints on dark matter annihilation signals, focusing on synchrotron radiation produced by electrons and positrons from dark matter interactions.

Contribution

It introduces a multi-frequency radio analysis to constrain dark matter annihilation, incorporating diffuse background data and substructure effects, highlighting astrophysical uncertainties.

Findings

Constraints of <sigma_A*v>=10^{-24} cm^3 s^{-1} for 100 GeV dark matter mass

Radio signals from bright clumps are heavily attenuated, limiting detection prospects

Results depend significantly on the galactic magnetic field model

Abstract

Annihilation of Dark Matter usually produces together with gamma rays comparable amounts of electrons and positrons. The e+e- gyrating in the galactic magnetic field then produce secondary synchrotron radiation which thus provides an indirect mean to constrain the DM signal itself. To this purpose, we calculate the radio emission from the galactic halo as well as from its expected substructures and we then compare it with the measured diffuse radio background. We employ a multi-frequency approach using data in the relevant frequency range 100 MHz-100 GHz, as well as the WMAP Haze data at 23 GHz. The derived constraints are of the order <sigma_A*v>=10^{-24} cm3 s^{-1} for a DM mass m_chi=100 GeV sensibly depending however on the astrophysical uncertainties, in particular on the assumption on the galactic magnetic field model. The signal from single bright clumps is instead largely attenuated by diffusion effects and offers only poor detection perspectives.