Shadow structure of generalized $k-n$ black-bounce metrics

Fuente: arXiv
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Autori principali: Nascimento, Jose R., Oliveira, Ana R. M., Petrov, Albert Yu., Porfírio, Paulo J., Queiroz, Amilcar R.
Natura: Preprint
Pubblicazione: 2025
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author Nascimento, Jose R.
Oliveira, Ana R. M.
Petrov, Albert Yu.
Porfírio, Paulo J.
Queiroz, Amilcar R.
author_facet Nascimento, Jose R.
Oliveira, Ana R. M.
Petrov, Albert Yu.
Porfírio, Paulo J.
Queiroz, Amilcar R.
contents The existence of black hole shadows is one of the most interesting effects of the strong field regime of general relativity (GR). Recent observations by the Event Horizon Telescope (EHT) have provided high-resolution images of the vicinity of supermassive black holes, ushering in a new era for testing gravitation on astrophysical scales. In this work, we continue the investigation initiated by \cite{furtado2025gravitational}, focusing on shadows associated with generalized $k-n$ \emph{black-bounce} type spacetimes, which smoothly interpolate between regular black holes and wormholes. We consider a generalization of the metric with free parameters $(a,k,n)$ that modify the mass function and enrich the possible phenomenology. We develop a semi-analytical study of photon orbits, obtaining the critical impact parameter and the shadow radius for different parameter combinations. Subsequently, we perform numerical ray-tracing simulations using the \textsc{GYOTO} code, incorporating optically thick accretion disks and varying the observation angle. Our results reveal characteristic signatures, including the formation of double-ring structures and deformations of the shadow radius, which can serve as observational discriminators between classical black holes and \emph{black-bounce} solutions.
format Preprint
id arxiv_https___arxiv_org_abs_2510_23748
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Shadow structure of generalized $k-n$ black-bounce metrics
Nascimento, Jose R.
Oliveira, Ana R. M.
Petrov, Albert Yu.
Porfírio, Paulo J.
Queiroz, Amilcar R.
General Relativity and Quantum Cosmology
High Energy Physics - Theory
The existence of black hole shadows is one of the most interesting effects of the strong field regime of general relativity (GR). Recent observations by the Event Horizon Telescope (EHT) have provided high-resolution images of the vicinity of supermassive black holes, ushering in a new era for testing gravitation on astrophysical scales. In this work, we continue the investigation initiated by \cite{furtado2025gravitational}, focusing on shadows associated with generalized $k-n$ \emph{black-bounce} type spacetimes, which smoothly interpolate between regular black holes and wormholes. We consider a generalization of the metric with free parameters $(a,k,n)$ that modify the mass function and enrich the possible phenomenology. We develop a semi-analytical study of photon orbits, obtaining the critical impact parameter and the shadow radius for different parameter combinations. Subsequently, we perform numerical ray-tracing simulations using the \textsc{GYOTO} code, incorporating optically thick accretion disks and varying the observation angle. Our results reveal characteristic signatures, including the formation of double-ring structures and deformations of the shadow radius, which can serve as observational discriminators between classical black holes and \emph{black-bounce} solutions.
title Shadow structure of generalized $k-n$ black-bounce metrics
topic General Relativity and Quantum Cosmology
High Energy Physics - Theory
url https://arxiv.org/abs/2510.23748