Evaporation of Echoing Black Holes

TL;DR

This paper investigates how a hypothetical reflective surface near a rotating black hole affects its evaporation process, revealing that such a surface can shorten the black hole's lifetime through resonant effects on emitted radiation.

Contribution

It introduces a model considering a reflective surface outside the horizon and demonstrates its impact on black hole evaporation and lifetime, incorporating quantum-gravitational effects.

Findings

Resonance modulates graybody factors in frequency space.

Reflective surface shortens black hole lifetime.

Numerical results show accelerated evaporation due to the cavity effect.

Abstract

We compute the graybody factor and evaporation rate of a rotating black hole in the presence of a hypothetical reflective surface slightly outside the outer horizon radius, assuming that it spontaneously emits thermal radiation due to quantum-gravitational effects such as firewalls or stretched horizons. As a result of a resonance caused by a cavity between the reflective surface and angular momentum barrier, the graybody factor is subject to a modulation in the frequency space. By taking into account this effect for multiangular modes of neutrinos, photons, and gravitons, we numerically compute the time development of the mass and angular momentum of the black hole, and show that the excited reflective surface shortens the lifetime of quantum black holes.