WIMP/FIMP dark matter and primordial black holes with memory burden effect

TL;DR

This paper explores how primordial black holes with memory effects can contribute to dark matter, analyzing the production and relic abundance of WIMPs and FIMPs without thermalization, and assessing gravitational freeze-in.

Contribution

It introduces the memory burden effect extending PBH lifetimes and provides conditions for non-thermalized dark matter production from PBHs, WIMPs, and FIMPs.

Findings

PBHs can survive longer due to the memory burden effect.

Dark matter can be composed of WIMPs, FIMPs, and PBHs without thermalization.

Gravitational freeze-in contribution is subdominant in the considered parameter space.

Abstract

The lifetime of primordial black holes (PBHs), which formed in the early universe, can be extended by the memory burden effect. Light PBHs may exist today and be candidates for dark matter (DM). We assume that DM is made of thermally produced weakly interacting massive particles (WIMPs), WIMPs produced via the Hawking radiation of PBHs, and PBHs that survived Hawking evaporation via the memory burden effect. Feebly interacting massive particles (FIMPs) are alternatives to WIMPs. Focusing on parameter regions where thermal production dominates and PBHs never dominate the energy density of the Universe, we identify a sufficient condition under which DM particles emitted from PBHs do not thermalize with the thermal bath. In this regime, the total DM relic abundance can be consistently obtained as the sum of the three components. In addition, we show that the contribution from gravitational freeze-in via graviton exchange remains subdominant within the parameter space considered.