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Main Authors: Khan, Muhammad Haider, Perlick, Volker
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2508.20575
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author Khan, Muhammad Haider
Perlick, Volker
author_facet Khan, Muhammad Haider
Perlick, Volker
contents We analyze gravitational lensing, in particular the shadow and photon rings, in the Ernst spacetime, also known as the Schwarzschild-Melvin spacetime, which describes a Schwarzschild black hole immersed in a homogenous magnetic field. Although the geodesic equation in this spacetime is chaotic, there are some relevant features that can be determined analytically. Among other things, we give analytic formulas for the vertical diameter of the shadow for an observer at arbitrary inclination and for the horizontal diameter of the shadow for an observer in the equatorial plane. Moreover, we use the strong-deflection formalism for analytically calculating the so-called photon rings of order $\ge 2$ and we use the recently introduced gap parameter $Δ_2$ for distinguishing lensing of an Ernst black hole from that of a Schwarzschild black hole.
format Preprint
id arxiv_https___arxiv_org_abs_2508_20575
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Lensing, Shadow and Photon Rings in a Magnetized Black Hole Spacetime
Khan, Muhammad Haider
Perlick, Volker
General Relativity and Quantum Cosmology
We analyze gravitational lensing, in particular the shadow and photon rings, in the Ernst spacetime, also known as the Schwarzschild-Melvin spacetime, which describes a Schwarzschild black hole immersed in a homogenous magnetic field. Although the geodesic equation in this spacetime is chaotic, there are some relevant features that can be determined analytically. Among other things, we give analytic formulas for the vertical diameter of the shadow for an observer at arbitrary inclination and for the horizontal diameter of the shadow for an observer in the equatorial plane. Moreover, we use the strong-deflection formalism for analytically calculating the so-called photon rings of order $\ge 2$ and we use the recently introduced gap parameter $Δ_2$ for distinguishing lensing of an Ernst black hole from that of a Schwarzschild black hole.
title Lensing, Shadow and Photon Rings in a Magnetized Black Hole Spacetime
topic General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2508.20575