Cogenesis of Baryon Asymmetry and Gravitational Dark Matter from Primordial Black Holes

TL;DR

This paper presents a model where primordial black hole evaporation produces dark matter and baryon asymmetry, with late entropy injection from right-handed neutrino decay ensuring observed relic abundances and structure formation compatibility.

Contribution

It introduces a unified scenario linking primordial black hole evaporation, dark matter production, and baryogenesis within a Type-I seesaw framework with late entropy dilution.

Findings

Dark matter can originate solely from PBH evaporation across a wide mass range.

Late entropy injection from RHN decay aligns PBH-produced DM with observed relic density.

Baryon asymmetry is generated via leptogenesis involving both thermal and PBH-produced RHNs.

Abstract

We propose a scenario where dark matter (DM) with a wide mass range from a few keV to PeV can be produced solely from evaporating primordial black holes (PBH), while being consistent with the required free streaming length for structure formation. If DM does not have any other interactions apart from gravity and the universe has a PBH dominated phase at early epoch, then PBH evaporation typically leads to overproduction of DM in this mass range. By incorporating this gravitational DM within a Type-I seesaw scenario with three right handed neutrinos (RHN), we bring the abundance of PBH generated DM within observed limits by late entropy injection due to decay of one of the RHNs, acting as the diluter. The diluter, due to its feeble coupling with the bath particles, gets produced primarily from the PBH evaporation thereby leading to the second stage of early matter domination after the end of PBH dominated era. The other two RHNs contribute to the origin of light neutrino mass and also lead to the observed baryon asymmetry via leptogenesis with contributions from both thermally and PBH generated RHNs. The criteria of DM relic and baryon asymmetry can be satisfied simultaneously if DM mass gets restricted to a ballpark in the MeV-GeV regime with the requirement of resonant leptogenesis for heavier DM mass in order to survive the large entropy dilution at late epochs.