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The present work explores the role of the dilaton charge $r_2$ and the plasma environment in explaining the observed images of M87* and Sgr A*. Dilaton charges are associated with Kerr-Sen black holes, the stationary, axi-symmetric black…

General Relativity and Quantum Cosmology · Physics 2025-12-09 Siddharth Kumar Sahoo , Indrani Banerjee

The Event Horizon Telescope (EHT), a global submillimeter wavelength very long baseline interferometry array, unveiled event-horizon-scale images of the supermassive black hole M87* as an asymmetric bright emission ring with a diameter of $…

General Relativity and Quantum Cosmology · Physics 2020-05-12 Rahul Kumar , Sushant G. Ghosh

We present a systematical study of static D >= 4 space-times of high symmetry with the matter source being a thin charged dust hypersurface shell. The shell manifold is assumed to have the following structure S_(beta) X R^(D-2-beta), beta…

General Relativity and Quantum Cosmology · Physics 2012-04-30 Martin Cermak , Martin Zouhar

There are now multiple direct probes of the region near black hole horizons, including direct imaging with the Event Horizon Telescope (EHT). As a result, it is now of considerable interest to identify what aspects of the underlying…

General Relativity and Quantum Cosmology · Physics 2023-11-06 Kiana Salehi , Avery Broderick , Boris Georgiev

The non-linearly coupled Einstein-matter field equations predict the existence of shadows with well-defined boundaries around black holes. We prove that, in spherically symmetric hairy black-hole spacetimes whose matter fields satisfy the…

General Relativity and Quantum Cosmology · Physics 2026-03-05 Shahar Hod

We develop a fully numerical framework to compute and visualize the \emph{hypershadow}\cite{Novo:2024wyn}, the three-dimensional generalization of the black hole shadow in five-dimensional spacetimes. Our method is based on backward ray…

General Relativity and Quantum Cosmology · Physics 2026-03-06 Jianzhi Yang

The observation of the shadows cast by the event horizon of black holes on the light emitted in its neighborhood is the target of current very-long-baseline-interferometric observations. When considering supermassive black holes, the light…

General Relativity and Quantum Cosmology · Physics 2019-02-20 Harrison Gott , Dimitry Ayzenberg , Nicolas Yunes , Anne Lohfink

The null geodesics of the regular and rotating magnetically charged black hole in a non-minimally coupled Einstein-Yang-Mills theory surrounded by a plasma medium is studied. The effect of magnetic charge and Yang-Mills parameter on the…

General Relativity and Quantum Cosmology · Physics 2022-07-25 Shubham Kala , Hemwati Nandan , Prateek Sharma

In this work, we investigate a spherically symmetric charged black hole in the presence of a Kalb--Ramond field background. We calculate the photon sphere and shadow radii and, corroborating our results, we constrain them from observational…

General Relativity and Quantum Cosmology · Physics 2024-07-10 F. Hosseinifar , A. A. Araújo Filho , M. Y. Zhang , H. Chen , H. Hassanabadi

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 recent discovery of the novel four-dimensional static and spherically symmetric Gauss-Bonnet black hole provides a promising bed to test Gauss-Bonnet gravity by using astronomical observations [Phys. Rev. Lett. 124, 081301 (2020)]. In…

General Relativity and Quantum Cosmology · Physics 2024-02-22 Shao-Wen Wei , Yu-Xiao Liu

The full metric describing two counter-rotating identical Kerr black holes separated by a massless strut is derived in the explicit analytical form. It contains three arbitrary parameters which are the Komar mass M, Komar angular momentum…

General Relativity and Quantum Cosmology · Physics 2008-12-30 V. S. Manko , E. D. Rodchenko , E. Ruiz , B. I. Sadovnikov

We derived an exact solution of the spherically symmetric Hayward black hole surrounded by perfect fluid dark matter (PFDM). By applying the Newman-Janis algorithm, we generalized it to the corresponding rotating black hole. Then, we…

General Relativity and Quantum Cosmology · Physics 2021-12-21 Tian-Chi Ma , He-Xu Zhang , Peng-Zhang He , Hao-Ran Zhang , Yuan Chen , Jian-Bo Deng

Observations of the black hole shadow of supermassive black holes, such as Sagittarius A* at the center of our Milky Way galaxy, allow us to study the properties of black holes and the nature of strong-field gravity. According to the Kerr…

General Relativity and Quantum Cosmology · Physics 2018-11-14 Dimitry Ayzenberg , Nicolas Yunes

In general relativity, the gyromagnetic ratio for all stationary, axisymmetric and asymptotically flat Einstein-Maxwell fields is known to be g=2. In this paper, we continue our previous works of examination this result for rotating charged…

High Energy Physics - Theory · Physics 2008-11-26 Alikram N. Aliev

We propose a new test of strong-field general relativity (GR) based on the universal interferometric signature of the black hole photon ring. The photon ring is a narrow ring-shaped feature, predicted by GR but not yet observed, that…

General Relativity and Quantum Cosmology · Physics 2020-12-09 Samuel E. Gralla , Alexandru Lupsasca , Daniel P. Marrone

Various astrophysical and cosmological observations today serve as an indirect evidence of the existence of dark matter in the universe. In the present work, we propose a class of spacetimes that show some important characteristics relevant…

General Relativity and Quantum Cosmology · Physics 2022-12-07 Ashok B. Joshi , Divya Tahelyani , Dipanjan Dey , Pankaj S. Joshi

Light passing near a black hole can follow multiple paths from an emission source to an observer due to strong gravitational lensing. Photons following different paths take different amounts of time to reach the observer, which produces an…

High Energy Astrophysical Phenomena · Physics 2024-11-25 George N. Wong , Lia Medeiros , Alejandro Cárdenas-Avendaño , James M Stone

Recent work in the literature has studied the quantum-mechanical decay of a Schwarzschild-like black hole, formed by gravitational collapse, into almost-flat space-time and weak radiation at a very late time. The relevant quantum amplitudes…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Elisabetta Di Grezia , Giampiero Esposito , Gennaro Miele

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