Electromagnetic Albedo of Quantum Black Holes

TL;DR

This paper calculates the electromagnetic reflectivity of quantum black hole horizons, revealing significant albedo at low energies due to collective plasma interactions, which could have observable implications.

Contribution

It introduces a novel collective interaction model for electromagnetic waves with Hawking plasma, challenging previous scattering-based assumptions.

Findings

Significant reflectivity of long wavelength photons off Hawking plasma.

Enhanced electromagnetic albedo at frequencies near Hawking temperature.

Two independent methods confirm the collective interaction effect.

Abstract

We compute the albedo (or reflectivity) of electromagnetic waves off the electron-positron Hawking plasma that surrounds the horizon of a Quantum Black Hole. We adopt the "modified firewall conjecture" for fuzzballs [arXiv:hep-th/0502050,arXiv:1711.01617], where we consider significant electromagnetic interaction around the horizon. While prior work has treated this problem as an electron-photon scattering process, we find that the incoming quanta interact collectively with the fermionic excitations of the Hawking plasma at low energies. We derive this via two different methods: one using relativistic plasma dispersion relation, and another using the one-loop correction to photon propagator. Both methods find that the reflectivity of long wavelength photons off the Hawking plasma is significant, contrary to previous claims. This leads to the enhancement of the electromagnetic albedo for frequencies comparable to the Hawking temperature of black hole horizons in vacuum. We comment on possible observable consequences of this effect.