Constraining spinning primordial black holes with global 21 cm signal

Abstract

Spin is a fundamental property of Primordial Black Holes, and it can substantially affect Primordial Black Holes (PBHs) evaporation rate. We consider the non-negligible spin of PBHs and study the bounds on the fraction of PBHs that accounts for dark matter as a function of mass and spin. Spinning Primordial Black Holes (SPBHs) can evaporate by Hawking radiation and inject energy into the intergalactic medium (IGM). The injection of the background radiation into IGM can significantly affect the thermal and ionization history of gas during cosmic dawn. Recently, the Experiment to Detect the Global Epoch of Reionization Signature (EDGES) low-band observation reported a 21 cm absorption signal in the redshift range 15-20. The presence of Hawking radiation by evaporating PBHs can modify the 21 cm absorption profile. Considering the EDGES signal into account, we constrain the fraction of SPBHs that accounts for dark matter as a function of mass and spin. We also compare these bound with other available observations.