Observing Micro Black Hole Dark Matter

TL;DR

This paper explores the possibility that primordial micro black holes, modified by extra dimensions or many species, could be viable dark matter candidates, with unique observational signatures and constraints from astrophysical phenomena.

Contribution

It analyzes the properties, stability, and observational consequences of micro black holes in modified gravity scenarios, highlighting their potential as dark matter and proposing new detection methods.

Findings

Micro black holes can be cosmologically stable under certain conditions.

Neutron star survival constrains micro black hole dark matter models.

Merger-induced evaporation bursts could serve as observational signatures.

Abstract

Primordial micro black holes can constitute dark matter if short-distance gravity is modified by extra dimensions or a large number of species and if the memory-burden effect sufficiently suppresses Hawking evaporation. The resulting black holes in the transition regime differ from their four-dimensional Einsteinian counterparts through their mass--radius relation, temperature, entropy, and lifetime, which can render even very light objects cosmologically stable. The most promising observational consequences of such micro black holes dark matter are analysed. Neutron star survival yields the most robust constraints, while a narrow region of parameter space can simultaneously remain viable and address the missing-pulsar problem in the Galactic center. Diffuse evaporation signals in neutrino telescopes are found to be relevant mainly in extra-dimensional scenarios, whereas in generic species models, visible emission is strongly suppressed by evaporation into dark sectors. Merger-induced evaporation bursts can provide an additional probe in extra-dimensional realisations if the post-merger remnant briefly returns to the semiclassical phase. Overall, micro black holes dark matter remains phenomenologically viable in constrained regions, with neutron stars, neutrino telescopes, and merger signatures providing complementary tests.