Perturbation theory for gravitational shadows in Kerr-like spacetimes

Fuente: arXiv
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Main Authors: Kobialko, Kirill, Gal'tsov, Dmitri
Format: Preprint
Published: 2025
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author Kobialko, Kirill
Gal'tsov, Dmitri
author_facet Kobialko, Kirill
Gal'tsov, Dmitri
contents We present a fully analytical method for calculating the key parameters of a Kerr-like gravitational shadow, including its horizontal and vertical diameters, $D_X$ and $D_Y$, the coordinates of its center $X_{C}$, the average radius $\bar{R}$, the deviation from sphericity $δC$, and the mean deviation from the Kerr shadow $δK$. Developed within the framework of perturbation theory, this approach yields all characteristic parameters as simple polynomial expressions with an accuracy of $\sim a^5$, where $a$ is the Kerr spin parameter. This eliminates the need for repeated numerical integration of cumbersome parametric equations. Furthermore, our derived formulas account for the effects of a plasma medium - a feature of particular relevance given the prospect of multi-frequency astrophysical observations.
format Preprint
id arxiv_https___arxiv_org_abs_2512_24126
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Perturbation theory for gravitational shadows in Kerr-like spacetimes
Kobialko, Kirill
Gal'tsov, Dmitri
General Relativity and Quantum Cosmology
We present a fully analytical method for calculating the key parameters of a Kerr-like gravitational shadow, including its horizontal and vertical diameters, $D_X$ and $D_Y$, the coordinates of its center $X_{C}$, the average radius $\bar{R}$, the deviation from sphericity $δC$, and the mean deviation from the Kerr shadow $δK$. Developed within the framework of perturbation theory, this approach yields all characteristic parameters as simple polynomial expressions with an accuracy of $\sim a^5$, where $a$ is the Kerr spin parameter. This eliminates the need for repeated numerical integration of cumbersome parametric equations. Furthermore, our derived formulas account for the effects of a plasma medium - a feature of particular relevance given the prospect of multi-frequency astrophysical observations.
title Perturbation theory for gravitational shadows in Kerr-like spacetimes
topic General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2512.24126