Bulk Black Hole Dark Matter

TL;DR

This paper explores how primordial black holes escaping into a dark dimension affect their viability as dark matter candidates, expanding the allowed mass range by relaxing previous confinement assumptions.

Contribution

It introduces the concept that PBHs can escape into the dark dimension and reevaluates their mass range as dark matter based on this new assumption.

Findings

PBHs can escape into the dark dimension almost instantaneously.

The allowed PBH mass range for dark matter is extended to 10^{11} - 10^{21} grams.

Escape into the dark dimension alters observational constraints on PBHs.

Abstract

The dark dimension provides a mechanism to resolve the cosmological hierarchy problem and assembles a colosseum for dark matter contenders. In a series of recent publications we investigated whether primordial black holes (PBHs) perceiving the dark dimension could constitute all of the dark matter in the universe. A key assumption of these investigations is that PBHs remain confined to the brane during the entire evaporation process. As a consequence, the abundance of PBHs evaporating at the present epoch is severely constrained by observations of both the extragalactic and Galactic $\gamma$-ray backgrounds. As a natural outgrowth of these investigations, herein we relax the assumption of brane localized PBHs and reexamine the evaporation process of PBHs which are allowed to escape into the dark dimension. We show that the escape of PBHs from the brane is almost instantaneous. Armed with this pivotal finding we reassess the allowed mass range of PBHs to assemble all cosmological dark matter, which is estimated to be $10^{11} \lesssim M_{\rm BH}/{\rm g} \lesssim 10^{21}$.