A dark matter interpretation for the ARCADE excess?

TL;DR

This paper explores whether dark matter annihilations or decays could explain the excess isotropic radio emission observed by ARCADE 2, proposing a novel dark matter interpretation for the phenomenon.

Contribution

It introduces a dark matter-based explanation for the ARCADE excess, linking WIMP annihilations to observed radio emissions with conservative assumptions.

Findings

Expected radio emission from light WIMPs matches ARCADE observations.

Dark matter annihilation could account for the excess without invoking unknown astrophysical sources.

The scenario is consistent with conservative clustering assumptions.

Abstract

The ARCADE 2 Collaboration has recently measured an isotropic radio emission which is significantly brighter than the expected contributions from known extra-galactic sources. The simplest explanation of such excess involves a "new" population of unresolved sources which become the most numerous at very low (observationally unreached) brightness. We investigate this scenario in terms of synchrotron radiation induced by WIMP annihilations or decays in extragalactic halos. Intriguingly, for light-mass WIMPs with thermal annihilation cross-section, and fairly conservative clustering assumptions, the level of expected radio emission matches the ARCADE observations.