Article
Astronomy & Astrophysics
A. Belhaj, H. Belmahi, M. Benali, W. El Hadri, H. El Moumni, E. Torrente-Lujan
Summary: This study investigates the shadow behaviors of five dimensional black holes embedded in type IIB superstring/supergravity inspired spacetimes, analyzing geometrical properties such as shapes and sizes. It is found that physical parameters significantly distort the shapes and decrease the size of the shadows. The research also delves into geometrical observables and energy emission rate aspects.
Article
Physics, Multidisciplinary
Fabio Bacchini, Daniel R. Mayerson, Bart Ripperda, Jordy Davelaar, Hector Olivares, Thomas Hertog, Bert Vercnocke
Summary: By imaging the shadows of horizonless fuzzball geometries in four-dimensional string theory, researchers have found that the microstructure of these fuzzballs can trap light rays near their would-be horizons. This phenomenon can be used to distinguish between fuzzballs near the scaling limit, which exhibit shadow similar to black holes without the paradoxes of event horizons, and alternative models of black compact objects based on observations of shadow size and residual glow.
PHYSICAL REVIEW LETTERS
(2021)
Article
Astronomy & Astrophysics
Ivo Sengo, Pedro V. P. Cunha, Carlos A. R. Herdeiro, Eugen Radu
Summary: We investigate the gravitational lensing by spinning Proca stars and Kerr black holes with Proca hair, discussing their theoretical aspects and observational constraints from EHT data. Theoretical analysis reveals the optical appearance and exotic features of these BHs, interpreted in terms of photon orbit structure. Observationally, the current EHT constraints are compatible with BHs formed from the superradiant instability of Kerr BHs. The resolution of future observations is estimated to better constrain this model.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Rahul Kumar, Balendra Pratap Singh, Md Sabir Ali, Sushant G. Ghosh
Summary: Due to the gravitational lensing effect, a black hole projects a shadow larger than its horizon over a bright background, and the shape and size can be calculated. The first direct image of a black hole produced by the Event Horizon Telescope collaboration is consistent with the shadow of a Kerr black hole according to general relativity. Deviations from the Kerr black hole due to modified theories of gravity are important for testing these theories through astrophysical observation.
PHYSICS OF THE DARK UNIVERSE
(2021)
Article
Astronomy & Astrophysics
Guo-Ping Li, Ke-Jian He
Summary: In this paper, the shadows and rings of the KS black hole in deformed HL gravity were carefully investigated using the ray-tracing method. The results show a decrease in certain parameters and an increase in effective potential with an increase in the omega parameter, with direct emissions dominating the total observed intensity.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Merce Guerrero, Gonzalo J. Olmo, Diego Rubiera-Garcia, Diego Saez-Chillon Gomez
Summary: By studying light rings and shadows, we found differences between black bounces and the Schwarzschild solution, as well as the optical appearance under three optical models.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Physics, Particles & Fields
Meirong Tang, Zhaoyi Xu
Summary: The successful observation of the M87 supermassive black hole using the EHT provides an opportunity to study the theory of gravity. In this study, the researchers obtained the exact solution for a rotating short-hair black hole and analyzed the effect of hairs on the black hole shadow. The results show that the rotation and scalar hairs have significant influences on the shape of the black hole shadow.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Astronomy & Astrophysics
Balendra Pratap Singh
Summary: In this work, the photon region and shadows of rotating black holes in the quintessential dark energy are studied when the observer is static in the domain of outer communication. The characteristics of the black hole shadow are determined by its mass, spin parameter, quintessential dark energy parameter, and normalization factor, with the state parameter significantly affecting the shape and size of the shadow. The geodesic equations of motion are generalized for the state parameter, allowing visualization of the black hole shadow by a static observer at any distance in the domain of outer communication. The angular diameter of the black hole shadow is estimated using the numerical values of the shadow radius and area, with specific values provided for the M87 and Sgr A* black holes.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Physics, Nuclear
Jiuyang Tang, Yunqi Liu, Wei-Liang Qian, Ruihong Yue
Summary: In this study, the effect of nonlinear electrodynamics on the shadows of charged, slowly rotating black holes with a cosmological constant is investigated. The trajectory of a photon, as a perturbation of the nonlinear electrodynamic field, is determined by an effective metric rather than the null geodesic of the background black hole spacetime. By analyzing the propagation of a discontinuity of the electromagnetic waveform, the effective metric can be derived and used to evaluate the image and shadow of the black hole using backward ray-tracing technique. The study explores the properties of black hole shadows in different scenarios of nonlinear electrodynamics and their dependence on other metric parameters.
Article
Astronomy & Astrophysics
Javlon Rayimbaev, Bushra Majeed, Mubasher Jamil, Kimet Jusufi, Anzhong Wang
Summary: In this article, we investigate the particle dynamics around a Bardeen-Kiselev black hole, including its geometrical properties, the dynamics of test particles, and the relationship with rotating Kerr black hole.
PHYSICS OF THE DARK UNIVERSE
(2022)
Article
Astronomy & Astrophysics
A. Belhaj, H. Belmahi, M. Benali, H. El Moumni, M. A. Essebani, M. B. Sedra
Summary: Using the Hamilton-Jacobi method, the study focuses on the optical shadows of rotating Bardeen-AdS black holes with internal and external field contributions. The analysis explores the effects of internal parameter contributions and dark energy on the shadow shape, and discusses the potential link to observations from the Event Horizon Telescope.
MODERN PHYSICS LETTERS A
(2022)
Article
Astronomy & Astrophysics
Arshia Anjum, Misba Afrin, Sushant G. Ghosh
Summary: In this paper, we study Kerr black holes surrounded by perfect dark fluid matter (PFDM) and analyze the effect of PFDM on photon orbits. We find that the azimuthal oscillations of photon boomerangs around rotating PFDM black holes behave differently for prograde and retrograde orbits. By using observational results from the Event Horizon Telescope (EHT), we obtain upper bounds on the PFDM parameter and conclude that rotating PFDM black holes could be strong candidates for astrophysical black holes.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Astronomy & Astrophysics
Ming Zhang, Jie Jiang
Summary: The acceleration of a black hole causes circular orbits for photons with fixed radial and latitude coordinates to deviate from the equatorial plane, altering the properties of the black hole shadow. As the acceleration increases, the latitude of the circular orbit also increases, leading to an increase in the observer's inclination angles, resulting in maximum shadow radius and distortion for an accelerating Kerr black hole.
Article
Astronomy & Astrophysics
Parth Bambhaniya, Dipanjan Dey, Ashok B. Joshi, Pankaj S. Joshi, Divyesh N. Solanki, Aadarsh Mehta
Summary: The shadow is not only a property of black holes, but can also be cast by naked singularities. Novel features of the shadow of naked singularities differentiate them from black holes observationally. Negative precession of bound timelike orbits and the simultaneous presence of shadow in deformed Kerr naked singularity spacetime may indicate the presence of a deformed Kerr naked singularity.
Article
Astronomy & Astrophysics
Kirill A. Bronnikov, Roman A. Konoplya, Thomas D. Pappas
Summary: The study presents a general parametrization method for describing spacetimes of spherically symmetric Lorentzian, traversable wormholes, with validity that extends beyond the weak field region. Experimental results show that the parametrization provides high accuracy at the first order in most cases.
Correction
Physics, Multidisciplinary
Takeshi Chiba, Fuminobu Takahashi, Masahide Yamaguchi
PHYSICAL REVIEW LETTERS
(2015)
Article
Physics, Multidisciplinary
Takeshi Chiba
PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS
(2015)
Article
Physics, Multidisciplinary
Takeshi Chiba, Shuichiro Yokoyama
PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS
(2017)
Article
Physics, Multidisciplinary
Takeshi Chiba, Masashi Kimura
PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS
(2017)
Article
Physics, Multidisciplinary
Junpei Ooba, Kiyotomo Ichiki, Takeshi Chiba, Naoshi Sugiyama
PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS
(2017)
Article
Astronomy & Astrophysics
Seiji Kawamura, Takashi Nakamura, Masaki Ando, Naoki Seto, Tomotada Akutsu, Ikkoh Funaki, Kunihito Ioka, Nobuyuki Kanda, Isao Kawano, Mitsuru Musha, Kazuhiro Nakazawa, Shuichi Sato, Takeshi Takashima, Takahiro Tanaka, Kimio Tsubono, Jun'ichi Yokoyama, Kazuhiro Agatsuma, Koh-suke Aoyanagi, Koji Arai, Akito Araya, Naoki Aritomi, Hideki Asada, Yoichi Aso, Dan Chen, Takeshi Chiba, Toshikazu Ebisuzaki, Satoshi Eguchi, Yumiko Ejiri, Motohiro Enoki, Yoshiharu Eriguchi, Masa-Katsu Fujimoto, Ryuichi Fujita, Mitsuhiro Fukushima, Toshifumi Futamase, Rina Gondo, Tomohiro Harada, Tatsuaki Hashimoto, Kazuhiro Hayama, Wataru Hikida, Yoshiaki Himemoto, Hisashi Hirabayashi, Takashi Hiramatsu, Feng-Lei Hong, Hideyuki Horisawa, Mizuhiko Hosokawa, Kiyotomo Ichiki, Takeshi Ikegami, Kaiki T. Inoue, Hideki Ishihara, Takehiko Ishikawa, Hideharu Ishizaki, Hiroyuki Ito, Yousuke Itoh, Kiwamu Izumi, Shinya Kanemura, Nobuki Kawashima, Fumiko Kawazoe, Naoko Kishimoto, Kenta Kiuchi, Shiho Kobayashi, Kazunori Kohri, Hiroyuki Koizumi, Yasufumi Kojima, Keiko Kokeyama, Wataru Kokuyama, Kei Kotake, Yoshihide Kozai, Hiroo Kunimori, Hitoshi Kuninaka, Kazuaki Kuroda, Sachiko Kuroyanagi, Kei-ichi Maeda, Hideo Matsuhara, Nobuyuki Matsumoto, Yuta Michimura, Osamu Miyakawa, Umpei Miyamoto, Shinji Miyoki, Mutsuko Y. Morimoto, Toshiyuki Morisawa, Shigenori Moriwaki, Shinji Mukohyama, Shigeo Nagano, Kouji Nakamura, Hiroyuki Nakano, Kenichi Nakao, Shinichi Nakasuka, Yoshinori Nakayama, Erina Nishida, Atsushi Nishizawa, Yoshito Niwa, Taiga Noumi, Yoshiyuki Obuchi, Naoko Ohishi, Masashi Ohkawa, Kenshi Okada, Norio Okada, Koki Okutomi, Kenichi Oohara, Norichika Sago, Motoyuki Saijo, Ryo Saito, Masaaki Sakagami, Shin-ichiro Sakai, Shihori Sakata, Misao Sasaki, Takashi Sato, Masaru Shibata, Kazunori Shibata, Ayumi Shimo-oku, Hisaaki Shinkai, Ayaka Shoda, Kentaro Somiya, Hajime Sotani, Aru Suemasa, Naoshi Sugiyama, Yudai Suwa, Rieko Suzuki, Hideyuki Tagoshi, Fuminobu Takahashi, Kakeru Takahashi, Keitaro Takahashi, Ryutaro Takahashi, Ryuichi Takahashi, Hirotaka Takahashi, Takamori Akiteru, Tadashi Takano, Nobuyuki Tanaka, Keisuke Taniguchi, Atsushi Taruya, Hiroyuki Tashiro, Yasuo Torii, Morio Toyoshima, Shinji Tsujikawa, Akitoshi Ueda, Ken-ichi Ueda, Takafumi Ushiba, Masayoshi Utashima, Yaka Wakabayashi, Kent Yagi, Kazuhiro Yamamoto, Toshitaka Yamazaki, Chul-Moon Yoo, Shijun Yoshida, Taizoh Yoshino
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2019)
Article
Astronomy & Astrophysics
Sachiko Kuroyanagi, Takeshi Chiba, Tomo Takahashi
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2018)
Article
Physics, Multidisciplinary
Takeshi Chiba
PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS
(2018)
Article
Astronomy & Astrophysics
Takuya Inoue, Eiichiro Komatsu, Wako Aoki, Takeshi Chiba, Toru Misawa, Tomonori Usuda
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN
(2020)
Article
Astronomy & Astrophysics
Takeshi Chiba, Fabio Chibana, Masahide Yamaguchi
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2020)
Article
Physics, Multidisciplinary
Seiji Kawamura, Masaki Ando, Naoki Seto, Shuichi Sato, Mitsuru Musha, Isao Kawano, Jun'ichi Yokoyama, Takahiro Tanaka, Kunihito Ioka, Tomotada Akutsu, Takeshi Takashima, Kazuhiro Agatsuma, Akito Araya, Naoki Aritomi, Hideki Asada, Takeshi Chiba, Satoshi Eguchi, Motohiro Enoki, Masa-Katsu Fujimoto, Ryuichi Fujita, Toshifumi Futamase, Tomohiro Harada, Kazuhiro Hayama, Yoshiaki Himemoto, Takashi Hiramatsu, Feng-Lei Hong, Mizuhiko Hosokawa, Kiyotomo Ichiki, Satoshi Ikari, Hideki Ishihara, Tomohiro Ishikawa, Yousuke Itoh, Takahiro Ito, Shoki Iwaguchi, Kiwamu Izumi, Nobuyuki Kanda, Shinya Kanemura, Fumiko Kawazoe, Shiho Kobayashi, Kazunori Kohri, Yasufumi Kojima, Keiko Kokeyama, Kei Kotake, Sachiko Kuroyanagi, Kei-ichi Maeda, Shuhei Matsushita, Yuta Michimura, Taigen Morimoto, Shinji Mukohyama, Koji Nagano, Shigeo Nagano, Takeo Naito, Kouji Nakamura, Takashi Nakamura, Hiroyuki Nakano, Kenichi Nakao, Shinichi Nakasuka, Yoshinori Nakayama, Kazuhiro Nakazawa, Atsushi Nishizawa, Masashi Ohkawa, Kenichi Oohara, Norichika Sago, Motoyuki Saijo, Masaaki Sakagami, Shin-ichiro Sakai, Takashi Sato, Masaru Shibata, Hisaaki Shinkai, Ayaka Shoda, Kentaro Somiya, Hajime Sotani, Ryutaro Takahashi, Hirotaka Takahashi, Takamori Akiteru, Keisuke Taniguchi, Atsushi Taruya, Kimio Tsubono, Shinji Tsujikawa, Akitoshi Ueda, Ken-ichi Ueda, Izumi Watanabe, Kent Yagi, Rika Yamada, Shuichiro Yokoyama, Chul-Moon Yoo, Zong-Hong Zhu
Summary: DECIGO is a future Japanese space mission aimed at detecting primordial gravitational waves and has other scientific objectives such as measuring the acceleration of the expansion of the Universe and predicting neutron star/black hole binary coalescences. DECIGO consists of four clusters of observatories placed in heliocentric orbit, with each cluster containing three spacecraft forming interferometers with a 1000 km arm length.
PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS
(2021)
Article
Physics, Multidisciplinary
Takeshi Chiba
Summary: A new scalar-tensor theory is introduced to study neutron stars, with results showing that the effective scalar coupling within observational constraints closely matches that derived from existing models. This suggests that constraints obtained by current models will be universal in limiting the curvature of coupling functions in the future.
PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS
(2022)
Article
Astronomy & Astrophysics
Takeshi Chiba, Shunichiro Kinoshita
Summary: This study introduces a proper time observable for a quantum clock and investigates the quantum time dilation in a weak gravitational field. The results show that the quantum time dilation in the weak gravitational field obeys a similar gravitational time dilation as predicted by classical relativity.
Proceedings Paper
Astronomy & Astrophysics
Shuichi Sato, Seiji Kawamura, Masaki Ando, Takashi Nakamura, Kimio Tsubono, Akito Araya, Ikkoh Funaki, Kunihito Ioka, Nobuyuki Kanda, Shigenori Moriwaki, Mitsuru Musha, Kazuhiro Nakazawa, Kenji Numata, Shin-ichiro Sakai, Naoki Seto, Takeshi Takashima, Takahiro Tanaka, Kazuhiro Agatsuma, Koh-suke Aoyanagi, Koji Arai, Hideki Asada, Yoichi Aso, Takeshi Chiba, Toshikazu Ebisuzaki, Yumiko Ejiri, Motohiro Enoki, Yoshiharu Eriguchi, Masa-Katsu Fujimoto, Ryuichi Fujita, Mitsuhiro Fukushima, Toshifumi Futamase, Katsuhiko Ganzu, Tomohiro Harada, Tatsuaki Hashimoto, Kazuhiro Hayama, Wataru Hikida, Yoshiaki Himemoto, Hisashi Hirabayashi, Takashi Hiramatsu, Feng-Lei Hong, Hideyuki Horisawa, Mizuhiko Hosokawa, Kiyotomo Ichiki, Takeshi Ikegami, Kaiki T. Inoue, Koji Ishidoshiro, Hideki Ishihara, Takehiko Ishikawa, Hideharu Ishizaki, Hiroyuki Ito, Yousuke Itoh, Nobuki Kawashima, Fumiko Kawazoe, Naoko Kishimoto, Kenta Kiuchi, Shiho Kobayashi, Kazunori Kohri, Hiroyuki Koizumi, Yasufumi Kojima, Keiko Kokeyama, Wataru Kokuyama, Kei Kotake, Yoshihide Kozai, Hideaki Kudoh, Hiroo Kunimori, Hitoshi Kuninaka, Kazuaki Kuroda, Kei-ichi Maeda, Hideo Matsuhara, Yasushi Mino, Osamu Miyakawa, Shinji Miyoki, Mutsuko Y. Morimoto, Tomoko Morioka, Toshiyuki Morisawa, Shinji Mukohyama, Shigeo Nagano, Isao Naito, Kouji Nakamura, Hiroyuki Nakano, Kenichi Nakao, Shinichi Nakasuka, Yoshinori Nakayama, Erina Nishida, Kazutaka Nishiyama, Atsushi Nishizawa, Yoshito Niwa, Taiga Noumi, Yoshiyuki Obuchi, Masatake Ohashi, Naoko Ohishi, Masashi Ohkawa, Norio Okada, Kouji Onozato, Kenichi Oohara, Norichika Sago, Motoyuki Saijo, Masaaki Sakagami, Shihori Sakata, Misao Sasaki, Takashi Sato, Masaru Shibata, Hisaaki Shinkai, Kentaro Somiya, Hajime Sotani, Naoshi Sugiyama, Yudai Suwa, Rieko Suzuki, Hideyuki Tagoshi, Fuminobu Takahashi, Kakeru Takahashi, Keitaro Takahashi, Ryutaro Takahashi, Ryuichi Takahashi, Tadayuki Takahashi, Hirotaka Takahashi, Takamori Akiteru, Tadashi Takano, Keisuke Taniguchi, Atsushi Taruya, Hiroyuki Tashiro, Yasuo Torii, Morio Toyoshima, Shinji Tsujikawa, Yoshiki Tsunesada, Akitoshi Ueda, Ken-ichi Ueda, Masayoshi Utashima, Yaka Wakabayashi, Hiroshi Yamakawa, Kazuhiro Yamamoto, Toshitaka Yamazaki, Jun'ichi Yokoyama, Chul-Moon Yoo, Shijun Yoshida, Taizoh Yoshino
11TH INTERNATIONAL LISA SYMPOSIUM
(2017)
Article
Astronomy & Astrophysics
Junpei Ooba, Kiyotomo Ichiki, Takeshi Chiba, Naoshi Sugiyama
