Quantum Insights on Primordial Black Holes as Dark Matter

Abstract

A recent understanding on how quantum effects may affect black-hole evolution opens new scenarios for dark matter, in connection with the presence of black holes in the very early universe. Quantum fluctuations of the geometry allow for black holes to decay into white holes via a tunnelling. This process yields to an explosion and possibly to a long remnant phase, that cures the information paradox. Primordial black holes undergoing this evolution constitute a peculiar kind of decaying dark matter, whose lifetime depends on their mass M and can be as short as M 2 . As smaller black holes explode earlier, the resulting signal have a peculiar fluence-distance relation. I discuss the different emission channels that can be expected from the explosion (sub-millimetre, radio, TeV) and their detection challenges. In particular, one of these channels produces an observed wavelength that scales with the redshift following a unique flattened wavelength-distance function, leaving a signature also in the resulting diffuse emission. I conclude presenting the first insights on the cosmological constraints, concerning both the explosive phase and the subsequent remnant phase.

Gravitational wave constraints on the primordial black hole dominated early universe

“…Interestingly, we may also be able to find hints of black hole remnants as dark matter [60], if PBH evaporation leaves Planck mass remnants behind as suggested by some quantum gravity theories [309][310][311][312][313] (see also Refs. [314][315][316][317]).…”

Probing primordial black hole scenarios with terrestrial gravitational wave detectors

“…Interestingly, we may also be able to find hints of black hole remnants as dark matter [63] if PBH evaporation leaves Planck mass remnants behind as suggested by some quantum gravity theories [325][326][327][328][329] (see also [330][331][332][333]). If so, there is a unique initial PBH mass, that is M ∼ 5 × 10 5 g, that can reheat the Universe and its remnants be the dark matter, with a sharp prediction for the frequency of induced GWs peaked at 100 Hz [63].…”

Considerations on Quantum Gravity Phenomenology

“…This scenario is attractive, difficult to falsify, but also hard to confirm. In this article, I do not cover the current work that explores its phenomenology [9]. What I intended to point out is that it might (well) be that we are already seeing a massive quantum gravity effect: dark matter.…”