Decoding infrared imprints of quantum origins of black holes

TL;DR

This paper explores the quantum structure of Kerr-Newman black holes, revealing their discrete mass spectrum, the transition to a continuum spectrum in the extremal limit, and universal relations across black hole classes, with implications for black hole emission and lifetime.

Contribution

It introduces a discretized geometric model for black hole entropy, demonstrating discrete mass states and universal length scale relations in Kerr-Newman black holes.

Findings

Black holes have non-continuous mass spectra with discrete steps.

The spectrum becomes continuous in the extremal limit.

The features are independent of extra spacetime dimensions.

Abstract

We analyze the emission spectrum of a (fundamentally quantum) black hole in the Kerr-Newman family by assuming a discretization of black hole geometry and the holographic entropy-area relation. We demonstrate that, given the above structure of black hole entropy, a macroscopic black hole always has non-continuously separated mass states and therefore they descend down in discrete manner. We evaluate the step size of the discrete spectrum, which vanishes in the extremal limit, leading to a continuum spectrum as expected from thermal nature of black holes. This further reveals an interesting relation, in each class, between the dynamic and kinematic length scales for all black holes belonging to the Kerr-Newman family, pointing towards a possible universal character across the class, dependent only on black hole mass. Further, we have presented the computation of maximum number of emitted quanta from the black hole as well as an estimation of its lifetime. We also argue the independence of these features from the presence of additional spacetime dimensions.