Probing Interacting Dark Energy and Scattering of Baryons with Dark Matter in Light of EDGES 21cm Signal

TL;DR

This paper investigates how interactions between dark energy and dark matter, along with baryon cooling via dark matter collisions, can explain the EDGES 21cm signal excess observed during cosmic dawn.

Contribution

It introduces and tests three dark matter-dark energy interaction models to explain the EDGES 21cm brightness temperature anomaly and explores their effects on cosmic evolution.

Findings

DM-DE interactions modify the Hubble parameter evolution.

Interactions influence the optical depth and baryon temperature.

Models can accommodate varied dark matter mass regimes.

Abstract

The EDGES experiment has observed an excess trough ($-500^{+200}_{-500}$ mK) in the brightness temperature $T_{21}$ of the 21cm absorption line of neutral Hydrogen atom (HI) from the era of cosmic dawn ($z \simeq 17.2$). We consider possible interaction of Dark Matter and Dark Energy fluid along with the cooling off of the baryon matter by its collision with Dark Matter to explain the observed excess trough of $T_{21}$. We make use of three different Dark Matter-Dark Energy (DM-DE) interaction models to taste the viability of those models in explaining the EDGES results. The evolution of Hubble parameter is modified by DM-DE interactions and this is also addressed in this work. This in turn influences the optical depth of HI 21cm as well as the baryon temperature and thus effects the $T_{21}$ brightness temperature. In addition we also find that the DM-DE interaction enables us to explore Dark Matter with varied mass regimes and their viabilities in terms of satisfying the EDGES result.