Primordial Black Holes are 5D

TL;DR

This paper explores how primordial black holes formed through known mechanisms in a specific quantum gravity framework are inherently five-dimensional, with potential observational signatures including high-energy neutrinos.

Contribution

It demonstrates that in the Dark Dimension Scenario, primordial black holes produced by standard mechanisms are necessarily five-dimensional, linking quantum gravity constraints to observable phenomena.

Findings

PBHs formed from cosmic strings can have lifetimes comparable to the universe's age.

Quantum gravity constraints imply PBHs are five-dimensional in this scenario.

Potential connection between high-energy neutrinos and five-dimensional PBHs.

Abstract

We revisit well-established mechanisms for primordial black hole (PBH) production, namely inflation, phase transitions, and cosmic strings, in the context of the Dark Dimension Scenario, which is motivated by Swampland principles. Applying quantum gravity constraints, we demonstrate that any viable mechanism, barring exotic new physics at low energies, inevitably leads to the formation of five-dimensional PBHs. We further show that PBHs formed from cosmic strings can have lifetimes comparable to the age of the universe. We comment on the observational implications of this result, including a potential connection to the recent detection of a high-energy neutrino by KM3NeT, whose energy is intriguingly close to the five-dimensional Planck scale in the Dark Dimension Scenario.