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The silhouette of a black hole having a critical curve (an unstable bound photon orbit) when illuminated by an optically thin accretion disk whose emission is confined to the equatorial plane shows a distinctive central brightness…

General Relativity and Quantum Cosmology · Physics 2022-05-11 Merce Guerrero , Gonzalo J. Olmo , Diego Rubiera-Garcia , Diego Sáez-Chillón Gómez

We construct theoretical investigation of the black hole shadow for rotating charged black hole in an asymptotically flat, axisymmetric, and stationary spacetime with Weyl corrections. This spacetime is characterized by mass ($M$), charge…

General Relativity and Quantum Cosmology · Physics 2019-06-11 Md Sabir Ali , Muhammed Amir

We investigate the shadow of a rotating braneworld black hole in dispersive plasma environments and assess the potential of the Event Horizon Telescope (EHT) observations to constrain braneworld gravity. The spacetime around a rotating…

General Relativity and Quantum Cosmology · Physics 2026-05-11 Siddharth Kumar Sahoo , Indrani Banerjee

We discuss the horizon properties, shadow cast, and the weak gravitational lensing of charged rotating regular black holes, which in addition to mass ($M$) and rotation parameter ($a$) have an electric charge ($Q$) and magnetic charge…

General Relativity and Quantum Cosmology · Physics 2019-12-12 Rahul Kumar , Sushant G. Ghosh , Anzhong Wang

We propose a new procedure for measuring the spin of a black hole with an unprecedented accuracy based on the gravitational lensing of millisecond pulsars. We derive the basic equations for lensing by a rotating black hole. We show that the…

General Relativity and Quantum Cosmology · Physics 2025-08-28 Amjad Ashoorioon , Mohammad Bagher Jahani Poshteh , Robert B. Mann

Shadows of black holes surrounded by an optically thin emitting medium have been extensively discussed in the literature. The Hioki-Maeda algorithm is a simple recipe to characterize the shape of these shadows and determine the parameters…

High Energy Astrophysical Phenomena · Physics 2015-12-04 Lingyun Yang , Zilong Li

We study the strong gravitational lensing on the equatorial plane of a quasi-Kerr compact object with arbitrary quadrupole moments which can be used to model the super-massive central object of the galaxy. We find that, when the quadrupolar…

General Relativity and Quantum Cosmology · Physics 2015-06-11 Changqing Liu , Songbai Chen , Jiliang Jing

The recent observation of the shadow of the supermassive compact object M87$^*$ by the Event Horizon Telescope (EHT) collaboration has opened up a new window to probe the strong gravity regime. In this paper, we study shadows cast by two…

General Relativity and Quantum Cosmology · Physics 2021-07-07 Rajibul Shaikh , Kunal Pal , Kuntal Pal , Tapobrata Sarkar

We investigate the properties of black hole shadows in the renormalization group (RG) improved Bonanno-Reuter spacetime, incorporating quantum gravitational corrections via the scale-dependent parameter $(\tilde{\omega})$ in a plasma…

General Relativity and Quantum Cosmology · Physics 2026-03-13 Shubham Kala

First sketch of black hole from M87 galaxy was obtained by Event Horizon Telescope, recently. As appearance of black hole shadow reflects space-time geometry of black holes, observations of black hole shadow may be a promising way to test…

General Relativity and Quantum Cosmology · Physics 2020-06-30 Zhe Chang , Qing-Hua Zhu

We study the motion of massless test particles in a five dimensional (5D) Myers-Perry black hole spacetime with two spin parameters. The behaviour of the effective potential in view of different values of black hole parameters is discussed…

General Relativity and Quantum Cosmology · Physics 2018-06-13 Ravi Shankar Kuniyal , Hemwati Nandan , Uma Papnoi , Rashmi Uniyal , K D Purohit

The optical appearance of a body compact enough to feature an unstable bound orbit, when surrounded by an accretion disk, is expected to be dominated by a luminous ring of radiation enclosing a central brightness depression typically known…

General Relativity and Quantum Cosmology · Physics 2023-09-25 Gonzalo J. Olmo , João Luís Rosa , Diego Rubiera-Garcia , Diego Sáez-Chillón Gómez

We investigate the standard relativistic geometrically thin and optically thick accretion disk in the background of a deformed compact object. The main purpose of this work is to determine whether such a deformed object possesses its own…

General Relativity and Quantum Cosmology · Physics 2025-05-26 Shokoufe Faraji

Kerr black holes are among the most intriguing predictions of Einstein's general relativity theory. These rotating massive astrophysical objects drag and intermix their surrounding space and time, deflecting and phase-modifying light…

General Relativity and Quantum Cosmology · Physics 2011-05-18 Fabrizio Tamburini , Bo Thidé , Gabriel Molina-Terriza , Gabriele Anzolin

This article computes the bending angle of a hairy black hole at weak field limits. The Gauss-Bonnet theorem is applied to the Gaussian optical curvature; this gives a way to calculate the hairy black hole light bending angle using the…

General Relativity and Quantum Cosmology · Physics 2025-02-25 Riasat Ali , Xia Tiecheng , Muhammad Awais , Rimsha Babar

In this letter, we investigate the strong gravitational lensing effects around two classes of rotating regular black holes, which behave as non-singular Minkowski core at the center. Starting from the null geodesic in the equatorial plane…

General Relativity and Quantum Cosmology · Physics 2025-01-07 Mingyu Guo , Menghe Wu , Hong Guo , Xiaomei Kuang , Fuyao Liu

We study the optical properties of the Kehagias-Sfetsos (KS) compact objects, characterized by the "Ho\v{r}ava" parameter $\omega_{_{KS}}$, in the presence of plasma, considering its homogeneous or power-law density distribution. The strong…

General Relativity and Quantum Cosmology · Physics 2022-10-19 Sudipta Hensh , Ahmadjon Abdujabbarov , Jan Schee , Zdeněk Stuchlík

We study strong gravitational lensing by a specific one-parameter extension of Kerr spacetime, a Kerr-like wormhole, characterized by a single parameter specifying the throat's location. We classify the roots of the radial potential derived…

General Relativity and Quantum Cosmology · Physics 2025-02-20 Tien Hsieh , Da-Shin Lee , Chi-Yong Lin

We consider applications of the curvature radius of a Kerr black hole shadow and propose three new approaches to simultaneously determine the black hole spin and inclination angle of the observer. The first one uses only two symmetric…

General Relativity and Quantum Cosmology · Physics 2019-09-27 Shao-Wen Wei , Yuan-Chuan Zou , Yu-Xiao Liu , Robert B. Mann

Quantum effects in general induce scale dependence in the coupling constants. We explore this possibility in gravity, with a scale-dependent Newton coupling. When applied to Kerr black holes with such a running coupling, the consistency of…

General Relativity and Quantum Cosmology · Physics 2026-02-19 Che-Yu Chen , Chiang-Mei Chen , Nobuyoshi Ohta