Lower bound on the radii of light rings in traceless black-hole spacetimes

Fuente: arXiv
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Autore principale: Hod, Shahar
Natura: Preprint
Pubblicazione: 2023
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author Hod, Shahar
author_facet Hod, Shahar
contents Photonspheres, curved hypersurfaces on which massless particles can perform closed geodesic motions around highly compact objects, are an integral part of generic black-hole spacetimes. In the present compact paper we prove, using analytical techniques, that the innermost light rings of spherically symmetric hairy black-hole spacetimes whose external matter fields are characterized by a traceless energy-momentum tensor cannot be located arbitrarily close to the central black hole. In particular, we reveal the physically interesting fact that the non-linearly coupled Einstein-matter field equations set the lower bound $r_γ\geq {6\over5}r_{\text{H}}$ on the radii of traceless black-hole photonspheres, where $r_{\text{H}}$ is the radius of the outermost black-hole horizon.
format Preprint
id arxiv_https___arxiv_org_abs_2311_17462
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Lower bound on the radii of light rings in traceless black-hole spacetimes
Hod, Shahar
General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
High Energy Physics - Theory
Photonspheres, curved hypersurfaces on which massless particles can perform closed geodesic motions around highly compact objects, are an integral part of generic black-hole spacetimes. In the present compact paper we prove, using analytical techniques, that the innermost light rings of spherically symmetric hairy black-hole spacetimes whose external matter fields are characterized by a traceless energy-momentum tensor cannot be located arbitrarily close to the central black hole. In particular, we reveal the physically interesting fact that the non-linearly coupled Einstein-matter field equations set the lower bound $r_γ\geq {6\over5}r_{\text{H}}$ on the radii of traceless black-hole photonspheres, where $r_{\text{H}}$ is the radius of the outermost black-hole horizon.
title Lower bound on the radii of light rings in traceless black-hole spacetimes
topic General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
High Energy Physics - Theory
url https://arxiv.org/abs/2311.17462