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Motivated by inclination of the Earth's orbit that is not located at galactic plane for observing the shadow of Sgr A*, we consider the black hole shadow for arbitrary inclinations and different velocities of observers. A surprising finding…

General Relativity and Quantum Cosmology · Physics 2021-09-07 Zhe Chang , Qing-Hua Zhu

In this paper, the shadow casted by the rotating black hole inspired by noncommutative geometry is investigated. In addition to the dimensionless spin parameter $a/M_{0}$ with $M_{0}$ black hole mass and inclination angle $i$, the…

General Relativity and Quantum Cosmology · Physics 2015-08-18 Shao-Wen Wei , Peng Cheng , Yi Zhong , Xiang-Nan Zhou

The recent time witnessed a surge of interest in strong gravitational lensing by black holes is due to the Event Horizon Telescope (EHT) results, which suggest comparing the black hole lensing in both general relativity and heterotic string…

General Relativity and Quantum Cosmology · Physics 2021-03-25 Sushant G. Ghosh , Rahul Kumar , Shafqat Ul Islam

Capturing the image of the shadow cast by the event horizon of an illuminated black hole is, at the most basic level, an experiment of extreme light deflection in a strongly curved spacetime. As such, the properties of an imaged shadow can…

General Relativity and Quantum Cosmology · Physics 2023-03-14 Kostas Glampedakis , George Pappas

We study the shadows of the fully non-linear, asymptotically flat Einstein-dilaton-Gauss-Bonnet (EdGB) black holes (BHs), for both static and rotating solutions. We find that, in all cases, these shadows are smaller than for comparable Kerr…

General Relativity and Quantum Cosmology · Physics 2017-03-22 Pedro V. P. Cunha , Carlos A. R. Herdeiro , Burkhard Kleihaus , Jutta Kunz , Eugen Radu

We analytically investigate the shadows cast by rotating black holes in the asymptotically safe gravity (ASG) by deriving complete null geodesics and observables using the Hamilton-Jacobi equation and Carter separable method. It turns out…

General Relativity and Quantum Cosmology · Physics 2020-07-13 Rahul Kumar , Balendra Pratap Singh , Sushant G. Ghosh

This work investigates several key aspects of a non--commutative theory with mass deformation. We calculate thermodynamic properties of the system and compare our results with recent literature. We examine the \textit{quasinormal} modes of…

General Relativity and Quantum Cosmology · Physics 2023-11-30 N. Heidari , H. Hassanabadi , A. A. Araújo Filho , J. Kriz , S. Zare , P. J. Porfírio

Black hole shadows and photon spheres offer valuable tools for investigating black hole properties. Recent observations by the Event Horizon Telescope Collaboration have confirmed the existence of rotating black holes. Black hole parameters…

General Relativity and Quantum Cosmology · Physics 2024-11-26 Vitalii Vertogradov , Ali Övgün , Reggie C. Pantig

In the wake of interest to find black hole solutions with scalar hair, we investigate the effects of disformal transformations on static spherically symmetric space-times with a non-trivial scalar field. In particular, we study solutions…

General Relativity and Quantum Cosmology · Physics 2020-04-22 Guillem Domènech , Atsushi Naruko , Misao Sasaki , Christof Wetterich

We consider a black hole mimicker given by an exact solution of the stationary and axially symmetric field equations in vacuum known as the $\delta$-Kerr metric. We study its optical properties based on a ray-tracing code for photon motion…

General Relativity and Quantum Cosmology · Physics 2022-07-25 Song Li , Temurbek Mirzaev , Ahmadjon A. Abdujabbarov , Daniele Malafarina , Bobomurat Ahmedov , Wen-Biao Han

The first image of black hole in M87 galaxy taken by Event Horizon Telescope shows that directed observation of supermassive black holes would be a promising way to test general relativity in strong gravity field regime. In order to…

General Relativity and Quantum Cosmology · Physics 2020-04-17 Zhe Chang , Qing-Hua Zhu

The first images of black hole shadows open new possibilities to constrain modern extended gravity theories. We present the method of shadow background calculation for black hole solutions in the form of Taylor series where $g_{11} = -…

General Relativity and Quantum Cosmology · Physics 2022-09-07 V. Prokopov , S. Alexeyev , O. Zenin

We study the shadow produced by a spinning Kaluza-Klein black hole in Einstein gravity coupled to a Maxwell field and a dilaton. The size and the shape of the shadow depend on the mass, the charge, and the angular momentum. We find that,…

General Relativity and Quantum Cosmology · Physics 2013-03-01 Leonardo Amarilla , Ernesto F. Eiroa

Recently, two of us have argued that non-Kerr black holes in gravity theories different from General Relativity may have a topologically non-trivial event horizon. More precisely, the spatial topology of the horizon of non-rotating and…

General Relativity and Quantum Cosmology · Physics 2012-04-16 Cosimo Bambi , Francesco Caravelli , Leonardo Modesto

Within 5-10 years, very-long baseline interferometry (VLBI) facilities will be able to directly image the accretion flow around SgrA$^*$, the super-massive black hole candidate at the center of the Galaxy, and observe the black hole…

General Relativity and Quantum Cosmology · Physics 2014-06-19 Naoki Tsukamoto , Zilong Li , Cosimo Bambi

No Kerr-like exact solution has yet been found in Chern-Simons modified gravity. Intrigued by this absence, we study stationary and axisymmetric metrics that could represent the exterior field of spinning black holes. For the standard…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Daniel Grumiller , Nicolas Yunes

The compact dark objects with very large masses residing at the centres of galaxies are believed to be black holes. Due to the gravitational lensing effect, they would cast a shadow larger than their horizon size over the background, whose…

Astrophysics · Physics 2008-11-26 Lei Huang , Mike Cai , Zhi-Qiang Shen , Feng Yuan

The study of astrophysical phenomena like black hole shadows is an effective approach to properly understand the modified gravity and explore its validity. Motivated by recent astrophysical observations, we consider a black hole (BH) in…

General Relativity and Quantum Cosmology · Physics 2025-03-20 Khadije Jafarzade , Zeynab Bazyar , Mubasher Jamil

The 2017 Event Horizon Telescope (EHT) observations of the central source in M87 have led to the first measurement of the size of a black-hole shadow. This observation offers a new and clean gravitational test of the black-hole metric in…

General Relativity and Quantum Cosmology · Physics 2020-10-05 Dimitrios Psaltis , Lia Medeiros , Pierre Christian , Feryal Ozel , Kazunori Akiyama , Antxon Alberdi , Walter Alef , Keiichi Asada , Rebecca Azulay , David Ball , Mislav Balokovic , John Barrett , Dan Bintley , Lindy Blackburn , Wilfred Boland , Geoffrey C. Bower , Michael Bremer , Christiaan D. Brinkerink , Roger Brissenden , Silke Britzen , Dominique Broguiere , Thomas Bronzwaer , Do-Young Byun , John E. Carlstrom , Andrew Chael , Chi-kwan Chan , Shami Chatterjee , Koushik Chatterjee , Ming-Tang Chen , Yongjun Chen , Ilje Cho , John E. Conway , James M. Cordes , Geoffrey B. Crew , Yuzhu Cui , Jordy Davelaar , Mariafelicia De Laurentis , Roger Deane , Jessica Dempsey , Gregory Desvignes , Jason Dexter , Ralph P. Eatough , Heino Falcke , Vincent L. Fish , Ed Fomalont , Raquel Fraga-Encinas , Per Friberg , Christian M. Fromm , Charles F. Gammie , Roberto García , Olivier Gentaz , Ciriaco Goddi , Jose L. Gomez , Minfeng Gu , Mark Gurwell , Kazuhiro Hada , Ronald Hesper , Luis C. Ho , Paul Ho , Mareki Honma , Chih-Wei L. Huang , Lei Huang , David H. Hughes , Makoto Inoue , Sara Issaoun , David J. James , Buell T. Jannuzi , Michael Janssen , Wu Jiang , Alejandra Jimenez-Rosales , Michael D. Johnson , Svetlana Jorstad , Taehyun Jung , Mansour Karami , Ramesh Karuppusamy , Tomohisa Kawashima , Garrett K. Keating , Mark Kettenis , Jae-Young Kim , Junhan Kim , Jongsoo Kim , Motoki Kino , Jun Yi Koay , Patrick M. Koch , Shoko Koyama , Michael Kramer , Carsten Kramer , Thomas P. Krichbaum , Cheng-Yu Kuo , Tod R. Lauer , Sang-Sung Lee , Yan-Rong Li , Zhiyuan Li , Michael Lindqvist , Rocco Lico , Jun Liu , Kuo Liu , Elisabetta Liuzzo , Wen-Ping Lo , Andrei P. Lobanov , Colin Lonsdale , Ru-Sen Lu , Jirong Mao , Sera Markoff , Daniel P. Marrone , Alan P. Marscher , Ivan Martí-Vidal , Satoki Matsushita , Yosuke Mizuno , Izumi Mizuno , James M. Moran , Kotaro Moriyama , Monika Moscibrodzka , Cornelia Muller , Gibwa Musoke , Alejandro Mus Mejías , Hiroshi Nagai , Neil M. Nagar , Ramesh Narayan , Gopal Narayanan , Iniyan Natarajan , Roberto Neri , Aristeidis Noutsos , Hiroki Okino , Hector Olivares , Tomoaki Oyama , Daniel C. M. Palumbo , Jongho Park , Nimesh Patel , Ue-Li Pen , Vincent Pietu , Richard Plambeck , Aleksandar PopStefanija , Ben Prather , Jorge A. Preciado-Lopez , Venkatessh Ramakrishnan , Ramprasad Rao , Mark G. Rawlings , Alexander W. Raymond , Bart Ripperda , Freek Roelofs , Alan Rogers , Eduardo Ros , Mel Rose , Arash Roshanineshat , Helge Rottmann , Alan L. Roy , Chet Ruszczyk , Benjamin R. Ryan , Kazi L. J. Rygl , Salvador Sanchez , David Sanchez-Arguelles , Mahito Sasada , Tuomas Savolainen , F. Peter Schloerb , Karl-Friedrich Schuster , Lijing Shao , Zhiqiang Shen , Des Small , Bong Won Sohn , Jason SooHoo , Fumie Tazaki , Remo P. J. Tilanus , Michael Titus , Pablo Torne , Tyler Trent , Efthalia Traianou , Sascha Trippe , Ilse van Bemmel , Huib Jan van Langevelde , Daniel R. van Rossum , Jan Wagner , John Wardle , Derek Ward-Thompson , Jonathan Weintroub , Norbert Wex , Robert Wharton , Maciek Wielgus , George N. Wong , Qingwen Wu , Doosoo Yoon , Andre Young , Ken Young , Ziri Younsi , Feng Yuan , Ye-Fei Yuan , Shan-Shan Zhao , the EHT Collaboration

Chameleon, environmentally dependent dilaton, and symmetron gravity are three models of modified gravity in which the effects of the additional scalar degree of freedom are screened in dense environments. They have been extensively studied…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 Anne-Christine Davis , Ruth Gregory , Rahul Jha , Jessica Muir