Probing interacting dark energy and scattering of baryons with dark matter in light of the EDGES 21-cm signal

The EDGES experiment has observed an excess trough (-500(-500)(+200) mK) in the brightness temperature T-21 of the 21-cm absorption line of neutral Hydrogen atom (HI) from the era of cosmic dawn (z similar or equal to 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 test 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 21-cm as well as the baryon temperature and thus effects the T-2(1), 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.

Automated summary

The EDGES experiment has observed an excess trough in the brightness temperature of the 21-cm absorption line of neutral Hydrogen atom from the era of cosmic dawn. Possible interactions between dark matter, dark energy, and baryon matter are considered to explain this excess trough. Different dark matter-dark energy interaction models are used to test their viability in explaining the observed results, with modifications to the evolution of the Hubble parameter also being addressed in this work.