Shadow of Extreme Compact Charged Objects in Consistent 4-Dimensional Einstein-Gauss-Bonnet Gravity

Fuente: arXiv
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Autores principales: Saghafi, Sara, Nozari, Kourosh, Kaveh, Maryam
Formato: Preprint
Publicado: 2025
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author Saghafi, Sara
Nozari, Kourosh
Kaveh, Maryam
author_facet Saghafi, Sara
Nozari, Kourosh
Kaveh, Maryam
contents In order to better describe gravitational phenomena on both very small and cosmological scales, there have been constant attempts to generalize and expand the theory of General Relativity (GR) since its inception. The Einstein Gauss Bonnet (EGB) theory is one such extension that adds spacetime corrections related to curvature. Since the standard Gauss Bonnet term is purely topological, it does not contribute to the field equations in four dimensions. To get around this restriction, however, an invariant four dimensional limit has been developed. In this work, we study Extreme Compact Charged Objects (ECCOs), which can resemble black holes, in a gravity framework that is compatible with Einstein Gauss Bonnet in four dimensions. Our main goal is to compare theoretical predictions with Event Horizon Telescope (EHT) observational data in order to constrain the Gauss Bonnet coupling constant α. In order to achieve this, we investigate important optical characteristics like the shadow, light bending angle, and other associated observables, as well as the geodesic structure of ECCO spacetimes in EGB gravity. Finally, we apply these findings to constrain the Gauss Bonnet constant.
format Preprint
id arxiv_https___arxiv_org_abs_2511_01533
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Shadow of Extreme Compact Charged Objects in Consistent 4-Dimensional Einstein-Gauss-Bonnet Gravity
Saghafi, Sara
Nozari, Kourosh
Kaveh, Maryam
General Relativity and Quantum Cosmology
High Energy Physics - Phenomenology
High Energy Physics - Theory
In order to better describe gravitational phenomena on both very small and cosmological scales, there have been constant attempts to generalize and expand the theory of General Relativity (GR) since its inception. The Einstein Gauss Bonnet (EGB) theory is one such extension that adds spacetime corrections related to curvature. Since the standard Gauss Bonnet term is purely topological, it does not contribute to the field equations in four dimensions. To get around this restriction, however, an invariant four dimensional limit has been developed. In this work, we study Extreme Compact Charged Objects (ECCOs), which can resemble black holes, in a gravity framework that is compatible with Einstein Gauss Bonnet in four dimensions. Our main goal is to compare theoretical predictions with Event Horizon Telescope (EHT) observational data in order to constrain the Gauss Bonnet coupling constant α. In order to achieve this, we investigate important optical characteristics like the shadow, light bending angle, and other associated observables, as well as the geodesic structure of ECCO spacetimes in EGB gravity. Finally, we apply these findings to constrain the Gauss Bonnet constant.
title Shadow of Extreme Compact Charged Objects in Consistent 4-Dimensional Einstein-Gauss-Bonnet Gravity
topic General Relativity and Quantum Cosmology
High Energy Physics - Phenomenology
High Energy Physics - Theory
url https://arxiv.org/abs/2511.01533