Optical appearance of black holes surrounded by a dark matter halo

Fuente: arXiv
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Main Authors: Macedo, Caio F. B., Rosa, João Luís, Rubiera-Garcia, Diego
Format: Preprint
Published: 2024
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author Macedo, Caio F. B.
Rosa, João Luís
Rubiera-Garcia, Diego
author_facet Macedo, Caio F. B.
Rosa, João Luís
Rubiera-Garcia, Diego
contents Black holes in General Relativity are described by space-time metrics that are simpler in comparison to non-vacuum compact objects. However, given the universality of the gravitational pull, it is expected that dark matter accumulates around astrophysical black holes, which can have an impact in the overall gravitational field, especially at galactic centers, and induce non-negligible effects in their observational imprints. In this work we study the optical appearance of a spherically symmetric black hole both when orbited by isotropically emitting light sources and when surrounded by a (geometrically and optically thin) accretion disk, while immersed in a dark matter halo. The black hole geometry plus the dark matter halo come as a solution of Einstein's field equations coupled to an anisotropic fluid whose density component follows a Hermquist-type distribution. Even in situations in which the geodesic description differs profoundly from the isolated black hole case, we find minor modifications to the primary and secondary tracks of the isotropic orbiting sources, and to the width, location, and relative luminosity of the corresponding photon rings as compared to the Schwarzschild black hole at equal black hole mass and emission models. This fact troubles distinguishing between both geometries using present observations of very-long baseline interferometry.
format Preprint
id arxiv_https___arxiv_org_abs_2402_13047
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Optical appearance of black holes surrounded by a dark matter halo
Macedo, Caio F. B.
Rosa, João Luís
Rubiera-Garcia, Diego
General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
Black holes in General Relativity are described by space-time metrics that are simpler in comparison to non-vacuum compact objects. However, given the universality of the gravitational pull, it is expected that dark matter accumulates around astrophysical black holes, which can have an impact in the overall gravitational field, especially at galactic centers, and induce non-negligible effects in their observational imprints. In this work we study the optical appearance of a spherically symmetric black hole both when orbited by isotropically emitting light sources and when surrounded by a (geometrically and optically thin) accretion disk, while immersed in a dark matter halo. The black hole geometry plus the dark matter halo come as a solution of Einstein's field equations coupled to an anisotropic fluid whose density component follows a Hermquist-type distribution. Even in situations in which the geodesic description differs profoundly from the isolated black hole case, we find minor modifications to the primary and secondary tracks of the isotropic orbiting sources, and to the width, location, and relative luminosity of the corresponding photon rings as compared to the Schwarzschild black hole at equal black hole mass and emission models. This fact troubles distinguishing between both geometries using present observations of very-long baseline interferometry.
title Optical appearance of black holes surrounded by a dark matter halo
topic General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2402.13047