Constraints on accreting primordial black holes with the global 21-cm
  signal
  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 $10\lesssim M_{\rm PBH}\lesssim 50~M_{\odot}$.
