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Starting from a recently constructed stealth Kerr solution of higher order scalar tensor theory involving scalar hair, we analytically construct disformal versions of the Kerr spacetime with a constant degree of disformality and a regular…

General Relativity and Quantum Cosmology · Physics 2021-01-07 Timothy Anson , Eugeny Babichev , Christos Charmousis , Mokhtar Hassaine

The astrophysical consequences of the presence of a quintessence scalar field on the evolution of the horizon and on the accretion disk surrounding a static black hole, in the Scalar-Vector-Tensor version of Modified Gravity (MOG), are…

General Relativity and Quantum Cosmology · Physics 2023-09-15 Haidar Sheikhahmadi , Saheb Soroushfar , S. N. Sajadi , Tiberiu Harko

In this work, we investigate geodesics and black hole shadows in the Kerr-Bertotti-Robinson spacetime. We show that the equations of motion for null geodesics are separable and admit analytical treatment, whereas timelike geodesics are…

General Relativity and Quantum Cosmology · Physics 2026-02-12 Xinyu Wang , Yehui Hou , Xi Wan , Minyong Guo , Bin Chen

The Event Horizon Telescope collaboration has revealed the first direct image of a black hole, as per the shadow of a Kerr black hole of general relativity. However, other Kerr-like rotating black holes of modified gravity theories cannot…

General Relativity and Quantum Cosmology · Physics 2022-01-21 Misba Afrin , Sushant G. Ghosh

Black holes in General Relativity are described by space-time metrics that are simpler in comparison to non-vacuum compact objects. However, given the universality of the gravitational pull, it is expected that dark matter accumulates…

General Relativity and Quantum Cosmology · Physics 2024-07-23 Caio F. B. Macedo , João Luís Rosa , Diego Rubiera-Garcia

We have investigated the shadow of a Konoplya-Zhidenko rotating non-Kerr black hole with an extra deformation parameter. The spacetime structure arising from the deformed parameter affects sharply the black hole shadow. With the increase of…

General Relativity and Quantum Cosmology · Physics 2017-11-01 Mingzhi Wang , Songbai Chen , Jiliang Jing

Collaborative international efforts under the name of the Event Horizon Telescope project, using sub- mm very long baseline interferometry, are soon expected to provide the first images of the shadow cast by the candidate supermassive black…

General Relativity and Quantum Cosmology · Physics 2016-10-26 Ziri Younsi , Alexander Zhidenko , Luciano Rezzolla , Roman Konoplya , Yosuke Mizuno

In the context of f(R) modified gravity theories, we study the Kerr-Newman black-hole solutions. We study non-zero constant scalar curvature solutions and discuss the metric tensor that satisfies the modified field equations. We determine…

General Relativity and Quantum Cosmology · Physics 2011-10-04 J. A. R. Cembranos , A. de la Cruz-Dombriz , P. Jimeno Romero

Gravitational wave observations can test the validity of General Relativity (GR) in the strong field regime. Certain classes of scalar-tensor theories indeed predict that compact objects can exhibit significant deviations from their GR…

General Relativity and Quantum Cosmology · Physics 2024-11-13 Georgios Antoniou , Caio F. B. Macedo , Andrea Maselli , Thomas P. Sotiriou

Black holes with dyonic charges in Einstein-Maxwell-dilaton-axion supergravity theory are revisited in the context of black hole shadows. We consider static as well as rotating (namely the dyonic Kerr-Sen) black holes. The matter…

General Relativity and Quantum Cosmology · Physics 2023-08-08 Soumya Jana , Sayan Kar

The distortion of the spacetime structure in the surroundings of black holes affects the trajectories of light rays. As a consequence, black holes can act as gravitational lenses. Observations of type Ia supernovas, show that our Universe…

General Relativity and Quantum Cosmology · Physics 2016-01-14 Ernesto F. Eiroa , Carlos M. Sendra

We study the shadow of a charged rotating black hole in $f(R)$ gravity. This black hole is characterized by mass, $M$, spin, $a$, electric charge, $Q$ and $R_{0}$ which is proportional to cosmological constant. We analyze the image of the…

General Relativity and Quantum Cosmology · Physics 2022-10-06 Sara Dastan , Reza Saffari , Saheb Soroushfar

In this paper, we investigate the strong gravitational lensing effects and optical appearances around a spherically symmetric regular black hole, whose metric is derived from a non-singular collapsing dust ball model in asymptotically safe…

General Relativity and Quantum Cosmology · Physics 2025-12-02 Xiao-Jun Gao

We examine the shadow of a rotating 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 of the compact object.…

General Relativity and Quantum Cosmology · Physics 2016-01-14 Leonardo Amarilla , Ernesto F. Eiroa

Recent observational data from the Event Horizon Telescope (EHT) collaboration provide convincing realistic evidence for the existence of black hole rotation. From a phenomenological perspective, a recently proposed stable rotating regular…

General Relativity and Quantum Cosmology · Physics 2025-01-15 Chen-Hao Xie , Yu Zhang , Qi Sun , Qi-Quan Li , Peng-Fei Duan

In this work, we investigate the shadow properties of the Kerr-Newman-Anti-de Sitter black hole coupled to a nonlinear electrodynamics. We construct the shadow by employing the celestial coordinate approach for observers located at finite…

General Relativity and Quantum Cosmology · Physics 2025-08-20 Mohsen Fathi

We review the constraints modified theories of gravity must satisfy to be compatible with the spherically symmetric black hole solutions of semiclassical gravity that describe the formation of an apparent horizon in finite time of a distant…

General Relativity and Quantum Cosmology · Physics 2023-01-30 Sebastian Murk

Recent developments in the field of gravitational physics, including the emergence of gravitational wave astronomy, black hole images, and more accurate telescopes, have allowed us to probe the strong-field character of gravity in a novel…

General Relativity and Quantum Cosmology · Physics 2023-08-08 Georgios Antoniou

In general relativity, isolated black holes are invisible due to an infinitely large redshift of photons propagating from the event horizon to the remote observer. However, the dark shadow (silhouette) of a black hole can be visible on the…

General Relativity and Quantum Cosmology · Physics 2020-08-31 Vyacheslav I. Dokuchaev , Natalia O. Nazarova

We calculate the characteristics of the "black hole shadow" for a rotating, neutral black hole in fourth-order conformal Weyl gravity. It is shown that the morphology is not significantly affected by the underlying framework, except for…

General Relativity and Quantum Cosmology · Physics 2018-04-13 Jonas R. Mureika , Gabriele U. Varieschi