Spectroscopy of a canonically quantized horizon

TL;DR

This paper derives observable deviations from Hawking radiation due to quantum horizon effects in loop quantum gravity, predicting spectral features that could test quantum gravity theories with astrophysical black holes.

Contribution

It introduces a quantum horizon model in loop quantum gravity that predicts specific spectral deviations and symmetries in black hole radiation spectra.

Findings

Spectral lines are enhanced due to quantum horizon effects.

The area spectrum exhibits unexpected evenly spaced symmetry.

Potential observational signatures for quantum gravity in black hole radiation.

Abstract

Deviations from Hawking's thermal black hole spectrum, observable for macroscopic black holes, are derived from a model of a quantum horizon in loop quantum gravity. These arise from additional area eigenstates present in quantum surfaces excluded by the classical isolated horizon boundary conditions. The complete spectrum of area unexpectedly exhibits evenly spaced symmetry. This leads to an enhancement of some spectral lines on top of the thermal spectrum. This can imprint characteristic features into the spectra of black hole systems. It most notably gives the signature of quantum gravity observability in radiation from primordial black holes, and makes it possible to test loop quantum gravity with black holes well above Planck scale.