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Autores principales: Wang, Yu-Yan, Zhao, Meng-Die, Wang, Xin-Yu, Li, Guo-Ping
Formato: Preprint
Publicado: 2025
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Acceso en línea:https://arxiv.org/abs/2511.06219
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author Wang, Yu-Yan
Zhao, Meng-Die
Wang, Xin-Yu
Li, Guo-Ping
author_facet Wang, Yu-Yan
Zhao, Meng-Die
Wang, Xin-Yu
Li, Guo-Ping
contents In this paper, we apply numerical backward ray-tracing to study the observational appearance of Kerr-Taub-NUT (KTN) black holes illuminated by thin accretion disk flows. We obtained the inner shadow, redshift characteristics, and intensity distribution of thin-disk images of the KTN black hole, as observed by a common observer located at different positions. The results show that increasing the spin parameter progressively deforms the critical curve into a "D" shape while simultaneously shrinking and distorting the inner shadow. More importantly, for n = 0.3 at theta_o = 80 degrees, the inner shadow develops a novel "duck-cap-like" morphology with a sharply protruding lower-right edge beyond the critical curve. We term this feature the "extended inner shadow", a structure distinct from the Kerr case. Unlike the standard inner shadow, it consists partly of photons absorbed by the horizon and partly of photons that avoid both absorption and crossing the disk plane, thus receiving no emission. Such deviations from Kerr predictions could be tested by future high-precision astronomical observations, potentially offering new evidence for the existence of NUT charge (or the gravitomagnetic monopole) in black holes.
format Preprint
id arxiv_https___arxiv_org_abs_2511_06219
institution arXiv
publishDate 2025
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spellingShingle The extended inner shadow of Kerr-Taub-NUT black hole with thin disk flows
Wang, Yu-Yan
Zhao, Meng-Die
Wang, Xin-Yu
Li, Guo-Ping
General Relativity and Quantum Cosmology
In this paper, we apply numerical backward ray-tracing to study the observational appearance of Kerr-Taub-NUT (KTN) black holes illuminated by thin accretion disk flows. We obtained the inner shadow, redshift characteristics, and intensity distribution of thin-disk images of the KTN black hole, as observed by a common observer located at different positions. The results show that increasing the spin parameter progressively deforms the critical curve into a "D" shape while simultaneously shrinking and distorting the inner shadow. More importantly, for n = 0.3 at theta_o = 80 degrees, the inner shadow develops a novel "duck-cap-like" morphology with a sharply protruding lower-right edge beyond the critical curve. We term this feature the "extended inner shadow", a structure distinct from the Kerr case. Unlike the standard inner shadow, it consists partly of photons absorbed by the horizon and partly of photons that avoid both absorption and crossing the disk plane, thus receiving no emission. Such deviations from Kerr predictions could be tested by future high-precision astronomical observations, potentially offering new evidence for the existence of NUT charge (or the gravitomagnetic monopole) in black holes.
title The extended inner shadow of Kerr-Taub-NUT black hole with thin disk flows
topic General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2511.06219