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

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 $10\lesssim M_{\rm PBH}\lesssim 50~M_{\odot}$.