Bounds on Dark Matter decay from 21 cm line

TL;DR

This paper demonstrates that 21-cm line observations can set conservative, astrophysics-independent bounds on dark matter decay rates, providing stronger limits than some existing methods using EDGES data.

Contribution

It introduces a new, model-independent method to constrain dark matter decay using 21-cm line measurements, surpassing previous bounds from CMB data.

Findings

Derived bounds on DM decay rates stronger than CMB constraints

Limits are valid for most DM models without extra IGM cooling

Results are competitive with indirect detection bounds

Abstract

The observation of the cosmic 21-cm spectrum can serve as a probe for Dark Matter properties. We point out that the knowledge of the signal amplitude at a given redshift allows one to put conservative bounds on the DM decay rate which are independent of astrophysical parameters. These limits are valid for the vast majority of DM models, those without extra IGM cooling or additional background radiation. Using the experimental results reported by the EDGES collaboration, we derive bounds that are stronger than the ones derived from other CMB observations and competitive with the ones from indirect detection.