Speaker
Description
We investigate Hawking evaporation of a population of primordial black holes (PBHs) as a novel mechanism to populate a dark sector which consists of self-interacting scalar dark matter with pure gravitational coupling to the visible sector. We demonstrate that depending on initial abundance of PBHs and the dark matter mass, the dark sector can reach chemical equilibrium with a temperature above, below, or equal to the temperature of the visible sector at the same time. Due to the absence of non-gravitational mediators between two sectors, any temperature asymmetry between two sectors will persist and evolve to keep the entropy of each sector conserved during the expansion of the Universe. We show that an equilibrated dark sector populated by Hawking evaporation of PBHs in an early radiation-dominated Universe can explain the dark matter relic abundance today for dark matter in the MeV-TeV mass range. We also show that populating the dark sector by evaporation of PBHs, when they dominate the energy density of the Universe, leads to overproduction of dark matter.
