Primordial regular black holes as all the dark matter. III. Covariant canonical quantum gravity models

TL;DR

This paper explores how quantum gravity corrections to primordial black holes influence their evaporation and abundance, suggesting they could still account for all dark matter but within a narrower mass range, based on a covariant canonical quantum gravity model.

Contribution

It extends previous phenomenological models by incorporating a covariant canonical quantum gravity approach, providing more theoretically grounded predictions for primordial black holes as dark matter candidates.

Findings

Quantum corrections increase black hole temperature, affecting evaporation spectra.

Stricter limits on primordial black hole abundance due to quantum effects.

Reduced mass window for primordial black holes to be all dark matter.

Abstract

In earlier companion papers, we showed that non-singular primordial black holes (PBHs) could account for all the dark matter (DM) over a significantly wider mass range compared to Schwarzschild PBHs. Those studies, mostly based on phenomenological metrics, are now extended by considering the quantum-corrected space-time recently proposed by Zhang, Lewandowski, Ma and Yang (ZLMY), derived from an effective canonical (loop) quantum gravity approach explicitly enforcing general covariance. Unlike the BHs considered earlier, ZLMY BHs are free from Cauchy horizons, and are hotter than their Schwarzschild counterparts. We show that this higher temperature boosts the evaporation spectra of ZLMY PBHs, tightening limits on their abundance relative to Schwarzschild PBHs and shrinking the asteroid mass window where they can constitute all the DM, a result which reverses the earlier trend, but rests on firmer theoretical ground. While stressing the potential key role of quantum gravity effects in addressing the singularity and DM problems, our study shows that working within a consistent theoretical framework can strongly affect observational predictions.