Light rings and causality for nonsingular ultracompact objects sourced by nonlinear electrodynamics

Fuente: arXiv
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Autori principali: Murk, Sebastian, Soranidis, Ioannis
Natura: Preprint
Pubblicazione: 2024
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author Murk, Sebastian
Soranidis, Ioannis
author_facet Murk, Sebastian
Soranidis, Ioannis
contents We study observational signatures of nonsingular ultracompact objects regularized by nonlinear electrodynamics. The phenomenon of birefringence causes photons of different polarizations to propagate with respect to two distinct metrics, which manifests itself in the appearance of additional light rings surrounding the ultracompact object. We analyze the observational consequences of this result and illustrate our findings based on three regular black hole models commonly considered in the literature. We find that nonsingular horizonless ultracompact objects sourced by nonlinear electrodynamics possess an odd number of light rings and discuss the viability of this model as an effective description of their properties. In addition, we compare the phase velocities of polarized light rays propagating in nonsingular geometries sourced by nonlinear electrodynamics to the corresponding phase velocity in the Schwarzschild spacetime and demonstrate that regularizing the singularity by means of a theory that does not adhere to the Maxwell weak-field limit may lead to the emergence of acausal regions.
format Preprint
id arxiv_https___arxiv_org_abs_2406_07957
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Light rings and causality for nonsingular ultracompact objects sourced by nonlinear electrodynamics
Murk, Sebastian
Soranidis, Ioannis
General Relativity and Quantum Cosmology
High Energy Physics - Theory
We study observational signatures of nonsingular ultracompact objects regularized by nonlinear electrodynamics. The phenomenon of birefringence causes photons of different polarizations to propagate with respect to two distinct metrics, which manifests itself in the appearance of additional light rings surrounding the ultracompact object. We analyze the observational consequences of this result and illustrate our findings based on three regular black hole models commonly considered in the literature. We find that nonsingular horizonless ultracompact objects sourced by nonlinear electrodynamics possess an odd number of light rings and discuss the viability of this model as an effective description of their properties. In addition, we compare the phase velocities of polarized light rays propagating in nonsingular geometries sourced by nonlinear electrodynamics to the corresponding phase velocity in the Schwarzschild spacetime and demonstrate that regularizing the singularity by means of a theory that does not adhere to the Maxwell weak-field limit may lead to the emergence of acausal regions.
title Light rings and causality for nonsingular ultracompact objects sourced by nonlinear electrodynamics
topic General Relativity and Quantum Cosmology
High Energy Physics - Theory
url https://arxiv.org/abs/2406.07957