Searching for the Dark Force with 21-cm Spectrum in Light of EDGES

TL;DR

This paper investigates how interactions between dark matter and dark sector components could influence the 21-cm spectrum, potentially explaining the EDGES absorption profile and offering new observational signatures for dark matter properties.

Contribution

It explores dark sector interactions and their effects on the 21-cm spectrum, providing constraints and potential observational signatures during dark ages.

Findings

Interaction models slightly relax dark matter parameter constraints

Dark sector interactions may produce detectable 21-cm signatures

Discrepancy with standard WIMP models remains

Abstract

The EDGES Collaboration has recently announced the detection of the 21-cm spectrum with an absorption profile centred at $78$ megahertz, of which the depth is deeper than that expected by the standard cosmological paradigm. To enrich the heating process of baryons due to scattering with dark matter during dark ages, we in this Letter explore the possibility of extra heat transfer between dark sector compositions and their observational signatures on the 21-cm cosmological spectrum. By parameterizing interaction models of the dark Universe, we find that the observational constraint on the parameter space of dark matter can be slightly relaxed but the discrepancy with the commonly predicted parameter space of weakly interacting massive particles remains. Our analyses also reveal that the interaction between dark compositions may leave observational signatures on the 21-cm spectrum during dark ages and thus would become detectable in the forthcoming 21-cm cosmology.