Escape of photons from two fixed extreme Reissner-Nordstr\"om black holes

TL;DR

This paper investigates the chaotic scattering of light by two fixed extreme Reissner-Nordstr"om black holes, identifying unstable periodic orbits and calculating escape rates through theoretical and numerical methods.

Contribution

It introduces a detailed analysis of photon escape dynamics in a static spacetime with two charged black holes, using periodic orbit theory and stability analysis.

Findings

Identification of the fractal repeller of unstable periodic orbits.

Calculation of the escape rate matching numerical simulations.

Analytical estimation of escape rate near a perturbed black hole.

Abstract

We study the scattering of light (null geodesics) by two fixed extreme Reissner-Nordstr\"om black holes, in which the gravitational attraction of their masses is exactly balanced with the electrostatic repulsion of their charges, allowing a static spacetime. We identify the set of unstable periodic orbits that constitute the fractal repeller that completely describes the chaotic escape dynamics of photons. In the framework of periodic orbit theory, the analysis of the linear stability of the unstable periodic orbits is used to obtain the main quantities of chaos that characterize the escape dynamics of the photons scattered by the black holes. In particular, the escape rate which is compared with the result obtained from numerical simulations that consider statistical ensembles of photons. We also analyze the dynamics of photons in the proximity of a perturbed black hole and give an analytical estimation for the escape rate in this system.