Constraints on accreting primordial black holes with the global 21-cm signal

TL;DR

This study uses the global 21-cm signal to place new constraints on the abundance of primordial black holes across a wide mass range, improving previous limits especially for lower masses.

Contribution

It introduces a method to constrain primordial black holes using the global 21-cm signal, accounting for baryonic and dark matter accretion effects on the IGM.

Findings

Stronger upper limits on PBH abundance for masses 10-50 M_sun.

Constraints extend to PBH masses up to 10^4 M_sun.

Results are based on EDGES 21-cm signal detection.

Abstract

We investigate the effect of accreting primordial black holes (PBHs) on the thermal history of the intergalactic medium (IGM), including the accretion of baryonic matter and dark matter particles. The variations of the thermal history of the IGM caused by accreting PBHs will result in the changes of the global 21-cm signal in the cosmic dawn. Based on the detection of the global 21-cm signal by EDGES, by requiring the differential brightness temperature, e.g., $\delta T_{21} \lesssim -100~(-50)~\rm mK$, we obtain the upper limits on the abundance of PBHs for the mass range $10\lesssim M_{\rm PBH} \lesssim 10^{4}~M_{\odot}$. Compared with previous works, the limits are stronger for the mass range $10\lesssim M_{\rm PBH}\lesssim 50~M_{\odot}$.