Could Planck Star Remnants be Dark Matter?

TL;DR

This paper proposes that stable Planck Star Remnants formed through quantum gravitational bounce mechanisms could be viable dark matter candidates, consistent with cosmological constraints and originating from primordial black hole evaporation.

Contribution

It introduces a model of nonsingular gravitational collapse in Loop Quantum Cosmology leading to stable remnants that could explain dark matter.

Findings

Remnants form via quantum bounce replacing singularity

Remnants are stable, non-radiating, and match Schwarzschild radius

Model aligns with astrophysical and cosmological constraints

Abstract

We explore the end state of gravitational collapse under quantum gravity effects and propose that Planck Star Remnants (PSR), formed via nonsingular bounces, could serve as viable dark matter candidates. Within the framework of Loop Quantum Cosmology, we model the collapse of a homogeneous matter distribution and show that the classical singularity is replaced by a quantum bounce at the Planck density. By analytically matching the Friedmann Lemaitre Robertson Walker (FLRW) interior to an exterior Schwarzschild spacetime using the Israel junction conditions, we demonstrate that the bounce remains causally hidden from external observers, avoiding any observable re-expansion. This naturally leads to the formation of stable, non-radiating PSR, whose radius coincides with the Schwarzschild radius when the black hole mass approaches the Planck mass as a result of Hawking evaporation. We suggest that such remnants may originate from evaporating primordial black holes in the early universe, and estimate the relic abundance needed for PSR to account for the observed dark matter density. We also discuss some crucial differences between PSR and previous proposals of Planck mass relics. The scenario is shown to be consistent with existing astrophysical and cosmological constraints, offering a unified framework connecting quantum gravitational collapse, and the nature of dark matter.