Galactic synchrotron emission from WIMPs at radio frequencies

TL;DR

This paper models the synchrotron radiation from dark matter annihilations in the Milky Way to set constraints on dark matter properties using radio frequency observations, highlighting the impact of astrophysical assumptions.

Contribution

It provides detailed calculations of synchrotron flux for various dark matter models and compares them with radio survey data to constrain dark matter parameters.

Findings

Current radio observations constrain dark matter with thermal cross-section and masses below 10 GeV.

Constraints depend on assumptions about galactic dark matter distribution and magnetic fields.

Future radio surveys could improve detection prospects for dark matter signals.

Abstract

Dark matter annihilations in the Galactic halo inject relativistic electrons and positrons which in turn generate a synchrotron radiation when interacting with the galactic magnetic field. We calculate the synchrotron flux for various dark matter annihilation channels, masses, and astrophysical assumptions in the low-frequency range and compare our results with radio surveys from 22 MHz to 1420 MHz. We find that current observations are able to constrain particle dark matter with "thermal" annihilation cross-sections, i.e. (\sigma v) = 3 x 10^-26 cm^3/s, and masses M_DM < 10 GeV. We discuss the dependence of these bounds on the astrophysical assumptions, namely galactic dark matter distribution, cosmic rays propagation parameters, and structure of the galactic magnetic field. Prospects for detection in future radio surveys are outlined.