Unveiling Inner Shadows and Polarization Signatures of Rotating Einstein-Gauss-Bonnet Black Holes

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Hauptverfasser: Chen, Bing-Bing, Yang, Chen-Yu, Chen, Deyou, He, Ke-Jian
Format: Preprint
Veröffentlicht: 2026
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author Chen, Bing-Bing
Yang, Chen-Yu
Chen, Deyou
He, Ke-Jian
author_facet Chen, Bing-Bing
Yang, Chen-Yu
Chen, Deyou
He, Ke-Jian
contents Based on the backward ray-tracing method, this paper numerically investigates the shadow and polarization images of rotating Einstein-Gauss-Bonnet (EGB) black hole within the framework of a thin disk model. We systematically analyze the effects of the main model parameters and the observation inclination angle $θ_o$ on both types of images. The results show that, as an intrinsic property of the black hole, the inner shadow undergoes significant deformation with increasing $θ_o$. The increase of the GB coupling constant $ξ$ only reduces the size of the inner shadow, while the spin parameter a does not alter its size but also its shape. And, the photon ring is more sensitive to variations in $θ_o$, while it is less affected by $ξ$ and $a$. For polarization images, the influence of $ξ$ on the polarization intensity is generally consistent with that observed in the accretion disk images. However, the polarization direction near the region of the inner shadow and photon ring changes significantly with $ξ$. This feature can provide an additional and effective observational tool for extracting information about the spacetime structure in Einstein-Gauss-Bonnet (EGB) gravity. Finally, we conclude that, compared to previous reliance on either accretion disk or polarization images alone, the simultaneous combination and synergistic analysis of both can more profoundly reveal the optical properties of rotating EGB black holes, providing a stronger theoretical basis for identifying such black holes through future high-resolution observations.
format Preprint
id arxiv_https___arxiv_org_abs_2604_07726
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Unveiling Inner Shadows and Polarization Signatures of Rotating Einstein-Gauss-Bonnet Black Holes
Chen, Bing-Bing
Yang, Chen-Yu
Chen, Deyou
He, Ke-Jian
General Relativity and Quantum Cosmology
Based on the backward ray-tracing method, this paper numerically investigates the shadow and polarization images of rotating Einstein-Gauss-Bonnet (EGB) black hole within the framework of a thin disk model. We systematically analyze the effects of the main model parameters and the observation inclination angle $θ_o$ on both types of images. The results show that, as an intrinsic property of the black hole, the inner shadow undergoes significant deformation with increasing $θ_o$. The increase of the GB coupling constant $ξ$ only reduces the size of the inner shadow, while the spin parameter a does not alter its size but also its shape. And, the photon ring is more sensitive to variations in $θ_o$, while it is less affected by $ξ$ and $a$. For polarization images, the influence of $ξ$ on the polarization intensity is generally consistent with that observed in the accretion disk images. However, the polarization direction near the region of the inner shadow and photon ring changes significantly with $ξ$. This feature can provide an additional and effective observational tool for extracting information about the spacetime structure in Einstein-Gauss-Bonnet (EGB) gravity. Finally, we conclude that, compared to previous reliance on either accretion disk or polarization images alone, the simultaneous combination and synergistic analysis of both can more profoundly reveal the optical properties of rotating EGB black holes, providing a stronger theoretical basis for identifying such black holes through future high-resolution observations.
title Unveiling Inner Shadows and Polarization Signatures of Rotating Einstein-Gauss-Bonnet Black Holes
topic General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2604.07726