Imprints of energy injection by compact dark stars in the 21-cm signal

Abstract

A strongly self-interacting component of asymmetric dark matter particles can form compact dark stars. The high dark matter density in these objects may allow significant dark matter annihilation into Standard Model particles, even when the portals to the visible sector are extremely weak. In this paper, we argue that compact dark stars could constitute an important source of energy injection during the cosmic dawn era in addition to that of the baryonic stars. Therefore, if dark stars annihilate into photons, the luminosity of dark stars may affect the reionization history of the Universe. We show that the evolution with the redshift of the temperature brightness of the 21-cm line could significantly deviate from the expectations of standard Cosmology, thus providing a new probe for particle dark matter.