Dynamical Heating from Dark Compact Objects and Axion Minihalos: Implications for the 21-cm Signal

TL;DR

This paper explores how dark compact objects and axion minihalos can heat baryons during the cosmic dark ages, and assesses the potential of upcoming 21-cm observations to detect such effects, thereby probing dark matter properties.

Contribution

It evaluates the detectability of dynamical friction-induced heating from dark compact objects and axion minihalos using future 21-cm experiments, highlighting improved sensitivity to dark matter substructures.

Findings

21-cm signals can detect dark compact objects as 10% of dark matter

Upcoming experiments will significantly improve axion-like particle constraints

Dynamical friction from dark structures influences baryon temperature during dark ages

Abstract

The temperature of baryons at the end of the cosmic dark ages can be inferred from observations of the 21-cm hyperfine transition in neutral hydrogen. Any energy injection from the dark sector can therefore be detected through these measurements. Dark compact objects and dark-matter substructures can modify the baryon temperature by transferring heat via dynamical friction. In this work, we evaluate the prospects for detecting dynamical friction-induced heating from dark compact objects with a mass in the range $10^2 M_{\odot}$ to $10^5 M_{\odot}$, as well as from axion minihalos, using upcoming 21-cm experiments. We find that both the 21-cm global signal and power-spectrum measurements will be sensitive to dark compact objects that constitute about 10% of the dark matter, and will substantially improve our sensitivity to axion-like particles with masses in the range $10^{-18}$ eV to $10^{-9}$ eV.