http://arxiv.org/abs/2103.07462
We are approaching a new era to probe the 21-cm neutral hydrogen signal from the period of cosmic dawn. This signal offers a unique window to the virgin Universe, e.g., to study dark matter models with different small-scale behaviours. The EDGES collaboration has recently published the first results of the global 21-cm spectrum. We demonstrate that such a signal can be used to set, unlike most observations concerning dark matter, both lower and upper limits for the mass of dark matter particles. We study the 21-cm signal resulting from a simple warm dark matter model with a sharp-$k$ window function calibrated for high redshifts. We tie the PopIII star formation to Lyman-alpha and radio background production. Using MCMC to sample the parameter space we find that to match the EDGES signal, a warm dark matter particle must have a mass of $7.3^{+1.6}{-3.3}$ keV at 68\% confidence interval. This translates to $2.2^{+1.4}{-1.7} \times 10^{-20}$ eV for fuzzy dark matter and $63^{+19}_{-35}$ keV for Dodelson-Widrow sterile neutrinos. Cold dark matter is unable to reproduce the signal due to its slow structure growth.
V. Vipp, A. Hektor and G. Hütsi
Mon, 15 Mar 21
30/36
Comments: Prepared for submission to PRD. Comments welcome!
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