Shadows and Polarization Images of a Four-dimensional Gauss-Bonnet Black Hole Irradiated by a Thick Accretion Disk
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arXiv
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| Autores principales: | , , , |
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| Formato: | Preprint |
| Publicado: |
2026
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| _version_ | 1866912951490838528 |
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| author | Zeng, Xiao-Xiong Ye, Huan Aslam, Muhammad Israr Saleem, Rabia |
| author_facet | Zeng, Xiao-Xiong Ye, Huan Aslam, Muhammad Israr Saleem, Rabia |
| contents | We adopt a general relativistic ray-tracing approach to study the shadows and polarization images of spherically symmetric Gauss-Bonnet (GB) black holes enveloped by geometrically thick accretion flows. Specifically, we adopt a phenomenological RIAF-like model and an analytical Hou disk model. In the RIAF-like model, increasing the GB coupling parameter $λ$ reduces both the size and brightness of the higher-order image, while increasing $θ$ alters the shape of the higher-order image and obscures the horizon's outline. The main difference between isotropic and anisotropic emission is that the latter produce distortion of the high-order image in the vertical direction, leading to an elliptical morphology. For the Hou disk model, due to specific regions being geometrically thinner with the conical approximation, the high-order images are narrower with the increase in $λ$ than the RIAF model. While increasing $θ$ enhances the brightness of the direct images outside the higher-order images, but hardly changes the size of the higher-order images, which is in sharp contrast to the RIAF model. Meanwhile, the Hou disk produces polarization patterns that trace the brightness configuration and are affected by $λ$ and $θ$, reflecting the intrinsic structure of spacetime. These results illustrate that intensity and polarization in thick-disk models provide probes of GB black holes and near-horizon accretion dynamics. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2603_07185 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Shadows and Polarization Images of a Four-dimensional Gauss-Bonnet Black Hole Irradiated by a Thick Accretion Disk Zeng, Xiao-Xiong Ye, Huan Aslam, Muhammad Israr Saleem, Rabia General Relativity and Quantum Cosmology High Energy Astrophysical Phenomena We adopt a general relativistic ray-tracing approach to study the shadows and polarization images of spherically symmetric Gauss-Bonnet (GB) black holes enveloped by geometrically thick accretion flows. Specifically, we adopt a phenomenological RIAF-like model and an analytical Hou disk model. In the RIAF-like model, increasing the GB coupling parameter $λ$ reduces both the size and brightness of the higher-order image, while increasing $θ$ alters the shape of the higher-order image and obscures the horizon's outline. The main difference between isotropic and anisotropic emission is that the latter produce distortion of the high-order image in the vertical direction, leading to an elliptical morphology. For the Hou disk model, due to specific regions being geometrically thinner with the conical approximation, the high-order images are narrower with the increase in $λ$ than the RIAF model. While increasing $θ$ enhances the brightness of the direct images outside the higher-order images, but hardly changes the size of the higher-order images, which is in sharp contrast to the RIAF model. Meanwhile, the Hou disk produces polarization patterns that trace the brightness configuration and are affected by $λ$ and $θ$, reflecting the intrinsic structure of spacetime. These results illustrate that intensity and polarization in thick-disk models provide probes of GB black holes and near-horizon accretion dynamics. |
| title | Shadows and Polarization Images of a Four-dimensional Gauss-Bonnet Black Hole Irradiated by a Thick Accretion Disk |
| topic | General Relativity and Quantum Cosmology High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2603.07185 |