Paper

Imprints of fermionic and bosonic mixed dark matter on the 21-cm signal at cosmic dawn

Giri, Sambit K, Schneider, Aurel

2022

Overview

The 21-cm signal from the epoch of cosmic dawn prior to reionization consists of a promising observable to gain new insights into the dark matter (DM) sector. In this paper, we investigate its potential to constrain mixed (cold + non-cold) dark matter scenarios that are characterised by the non-cold DM fraction (\\(f_ nCDM\\)) and particle mass (\\(m_ nCDM\\)). As non-cold DM species, we investigate both a fermionic (sterile neutrino) and a bosonic (ultra-light axion) particle. We show how these scenarios affect the global signal and the power spectrum using a halo-model implementation of the 21-cm signal at cosmic dawn. Next to this study, we perform an inference-based forecast study based on realistic mock power spectra from the Square Kilometre Array (SKA) telescope. Assuming inefficient, yet non-zero star-formation in minihaloes (i.e. haloes with mass below \\(10^8\\) M\\(_\\)), we obtain stringent constraints on both \\(m_ nCDM\\) and \\(f_ nCDM\\) that go well beyond current limits. Regarding the special case of \\(f_ nCDM 1\\), for example, we find a constraint of \\(m_ nCDM>15\\) keV (thermal mass) for fermionic DM and \\(m_ nCDM>210^-20\\) eV for bosonic DM. For the opposite case of dominating cold DM, we find that at most one percent of the total DM abundance can be made of a hot fermionic or bosonic relic. All constraints are provided at the 95 percent confidence level.

• Publisher: Cornell University Library, arXiv.org
• Subject: Cold / Confidence intervals / Dark matter / Ionization / Neutrinos / Particle mass / Power spectra / Space telescopes / Star formation