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Aims. In order to understand the anisotropic properties of local radiation field in the curved spacetime around a rotating black hole, we investigate the appearance of a black hole seen by an observer located near the black hole. When the…

High Energy Astrophysical Phenomena · Physics 2015-05-18 Rohta Takahashi , Masaaki Takahashi

We consider the black hole (BH) shadow images which can be restored by data processing and image recovery procedures in future space Very Large Baseline Interferometry (VLBI) missions. For Kerr BHs with masses and coordinates of SgrA*, M87*…

Astrophysics of Galaxies · Physics 2020-08-26 E. V. Mikheeva , S. V. Repin , V. N. Lukash

We have studied the shadows of a circular disformal Kerr black hole with a deformation parameter, which represents a rotating solution within a generalized scalar-tensor framework of Horndeski gravity that characterized by second-order…

General Relativity and Quantum Cosmology · Physics 2026-01-06 Fen Long , Songbai Chen , Jiliang Jing

We set out to bridge the gap between regular black-hole spacetimes and observations of a black-hole shadow by the Event Horizon Telescope. We explore modifications of spinning and non-spinning black-hole spacetimes inspired by…

General Relativity and Quantum Cosmology · Physics 2019-06-19 Aaron Held , Roman Gold , Astrid Eichhorn

In this paper, we investigate the observational appearances of magnetically charged black holes in Born-Infeld (BI) electrodynamics. We examine the effects of the magnetic charge and the BI parameter on the geodesics with different impact…

General Relativity and Quantum Cosmology · Physics 2023-04-20 Shangyu Wen , Wei Hong , Jun Tao

We investigate the shadow behaviors of the superentropic black holes in arbitrary dimensions. Using the Hamilton-Jacobi mechanism, we first obtain the associated null geodesic equations of motion. By help of a spheric stereographic…

High Energy Physics - Theory · Physics 2022-08-10 A. Belhaj , M. Benali , Y. Hassouni

We use data from M87* central black hole shadow, as well as from the S2 star observations, in order to extract constraints on Barrow entropy. The latter is a modified entropy arising from quantum-gravitational effects on the black hole…

General Relativity and Quantum Cosmology · Physics 2022-02-08 Kimet Jusufi , Mustapha Azreg-Aïnou , Mubasher Jamil , Emmanuel N. Saridakis

Metric of axially symmetric asymptotically flat black holes in an arbitrary metric theory of gravity can be represented in the general form which depends on infinite number of parameters. We constrain this general class of metrics by…

General Relativity and Quantum Cosmology · Physics 2021-05-20 R. A. Konoplya , A. Zhidenko

We investigated a modified Frolov black hole (BH) model that incorporates both a global monopole (GM) and a cosmic string (CS) to explore the interplay between non-singular BH regularization and topological defect effects. In our study, we…

General Relativity and Quantum Cosmology · Physics 2025-04-21 Faizuddin Ahmed , Ahmad Al-Badawi , İzzet Sakallı

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

We show that, away from the axis of symmetry, no continuous degeneration exists between the shadows of observers at any point in the exterior region of any Kerr-Newman black hole spacetime of unit mass. Therefore, except possibly for…

General Relativity and Quantum Cosmology · Physics 2024-10-29 Marc Mars , Claudio F. Paganini , Marius A. Oancea

Recent observations of black hole shadows have revolutionized our ability to probe gravity in extreme environments. This manuscript presents a novel analytic method to calculate, in leading-order terms, the key parameters of photon sphere…

General Relativity and Quantum Cosmology · Physics 2024-06-04 Vitalii Vertogradov , Ali Övgün

We study the shadow behaviors of five dimensional (5D) black holes embedded in type IIB superstring/supergravity inspired spacetimes by considering solutions with and without rotations. Geometrical properties as shapes and sizes are…

High Energy Physics - Theory · Physics 2020-12-23 A. Belhaj , H. Belmahi , M. Benali , W. El Hadri , H. El Moumni , E. Torrente-Lujan

We establish a thermodynamic-optical duality that directly bridges the semiclassical quantum evaporation of black holes with their classical macroscopic geometry. By employing a diffeomorphic inversion, we re-parameterize the intrinsic…

General Relativity and Quantum Cosmology · Physics 2026-04-27 Nikko John Leo S. Lobos , Emmanuel T. Rodulfo

This paper studies the black hole shadow, absorption cross section, and Hawking radiation of a massless scalar field in the background of a static spherically symmetric black hole spacetime that is surrounded by a cloud of strings in…

General Relativity and Quantum Cosmology · Physics 2023-07-11 Qian Li , Chen Ma , Yu Zhang , Zhi-Wen Lin , Peng-Fei Duan

We explore the structure of shadow for a Kerr-de Sitter black hole with a non-magnetized, pressureless plasma surrounding it. Specific plasma distributions are considered to separate the Hamilton-Jacobi equation and find the photon regions.…

General Relativity and Quantum Cosmology · Physics 2021-09-16 Abhishek Chowdhuri , Arpan Bhattacharyya

Can we determine a spin parameter of a black hole by observation of a black hole shadow in an accretion disk? In order to answer this question, we make a qualitative analysis and a quantitative analysis of a shape and a position of a black…

Astrophysics · Physics 2011-05-10 Rohta Takahashi

We present a comprehensive theoretical study of geodesic motion and thermodynamic behavior in Kalb--Ramond (KR) black hole (BH) spacetimes sourced by ModMax electrodynamics. Both neutral and charged test particle dynamics are investigated,…

General Relativity and Quantum Cosmology · Physics 2025-08-06 Faizuddin Ahmed , Ahmad Al-Badawi , İzzet Sakallı

We study the influence of the plasma environment on the shadows of stationary axisymmetric wormholes. We consider a sample of several wormhole solutions and plasma distributions for which the Hamilton-Jacobi equation for the light rays is…

General Relativity and Quantum Cosmology · Physics 2025-12-16 Tsanimir Angelov , Rasim Bekir , Galin Gyulchev , Petya Nedkova , Stoytcho Yazadjiev

We study the shadows cast by near-extremal Kerr-MOG black holes for different values of the parameter in modified gravity (MOG). In particular, we consider an isotropic emitter orbiting near such black holes and analytically compute the…

General Relativity and Quantum Cosmology · Physics 2018-11-12 Minyong Guo , Niels A. Obers , Haopeng Yan