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Main Authors: Li, Long-Yue, Cao, Li-Ming, Gong, Yungui, Liu, Xia-Yuan, Zhou, Wenting
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2602.07923
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author Li, Long-Yue
Cao, Li-Ming
Gong, Yungui
Liu, Xia-Yuan
Zhou, Wenting
author_facet Li, Long-Yue
Cao, Li-Ming
Gong, Yungui
Liu, Xia-Yuan
Zhou, Wenting
contents Applying the junction conditions to the slowly rotating Kerr spacetime with a thin shell, we find that while the angular momentum $L$ and Carter constant $C$ of the ray remain unchanged upon crossing the shell, its energy $E$ does not. Consequently, the impact parameters $η=L/E$ and $ξ=C/E^2$ of the ray are discontinued at the shell. Utilizing this transformation, we study the shadow of this spacetime and the corresponding images from an equatorial thin accretion disk. The presence of the shell gives rise to distinctive features in the observed images. Notably, we observe distinct double photon rings in the images, which can gradually merge into a single ring. Moreover, the shadow boundaries and the photon rings do not exhibit a one-to-one correspondence. The abrupt changes in redshift factor and the truncated photon regions profoundly influence the image, producing distinctive features such as the step-like structures. These features in shell-equipped spacetimes can help evaluate, through future astronomical observations, the applicability of the Israel junction condition and the shell model in real astrophysical systems.
format Preprint
id arxiv_https___arxiv_org_abs_2602_07923
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Signatures of the Israel Junction II: Double Photon Rings in Slowly Rotating Kerr Spacetime with Thin Shell
Li, Long-Yue
Cao, Li-Ming
Gong, Yungui
Liu, Xia-Yuan
Zhou, Wenting
General Relativity and Quantum Cosmology
Applying the junction conditions to the slowly rotating Kerr spacetime with a thin shell, we find that while the angular momentum $L$ and Carter constant $C$ of the ray remain unchanged upon crossing the shell, its energy $E$ does not. Consequently, the impact parameters $η=L/E$ and $ξ=C/E^2$ of the ray are discontinued at the shell. Utilizing this transformation, we study the shadow of this spacetime and the corresponding images from an equatorial thin accretion disk. The presence of the shell gives rise to distinctive features in the observed images. Notably, we observe distinct double photon rings in the images, which can gradually merge into a single ring. Moreover, the shadow boundaries and the photon rings do not exhibit a one-to-one correspondence. The abrupt changes in redshift factor and the truncated photon regions profoundly influence the image, producing distinctive features such as the step-like structures. These features in shell-equipped spacetimes can help evaluate, through future astronomical observations, the applicability of the Israel junction condition and the shell model in real astrophysical systems.
title Signatures of the Israel Junction II: Double Photon Rings in Slowly Rotating Kerr Spacetime with Thin Shell
topic General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2602.07923