In, Through and Beyond the Planck Scale

TL;DR

This paper explores loop quantum black holes, revealing a self-dual metric under T-duality, and suggests small, stable black holes could account for dark matter and produce observable ultra-high-energy cosmic rays.

Contribution

It introduces a self-dual semiclassical metric for loop quantum black holes and discusses their potential role as dark matter candidates and sources of cosmic rays.

Findings

Small LQBHs are stable and could be dark matter components.

Ultra-light LQBHs emit high-energy radiation and cosmic rays.

Production of UHECRs by LQBHs aligns with observations.

Abstract

In this paper we have recalled the semiclassical metric obtained from a classical analysis of the loop quantum black hole (LQBH). We show that the regular Reissner-Nordstr\"om-like metric is self-dual in the sense of T-duality: the form of the metric is invariant under the exchange r -> a0/r where a0 is proportional to the minimum area in LQG. Of particular interest, the symmetry imposes that if an observer at infinity sees a black hole of mass m an observer in the other asymptotic infinity beyond the horizon (near r=0) sees a dual mass proportional to m_P^2/m. We then show that small LQBHs are stable and could be a component of dark matter. Ultra-light LQBHs created shortly after the Big Bang would now have a mass of approximately 10^(-5) m_P and emit radiation with a typical energy of about 10^(13) - 10^(14) eV but they would also emit cosmic rays of much higher energies, albeit few of them. If these small LQBHs form a majority of the dark matter of the Milky Way's Halo, the production rate of ultra-high-energy-cosmic-rays (UHECR) by these ultra light black holes would be compatible with the observed rate of the Auger detector.