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Using the general parametrization of spherically symmetric and asymptotically flat black holes in arbitrary metric theories of gravity and implying that: a) the post-Newtonian constraints are taken into account and b) basic astrophysically…

General Relativity and Quantum Cosmology · Physics 2023-08-10 R. A. Konoplya , A. Zhidenko

This article delves into the observational properties of a Schwarzschild-like black hole (BH). Initially, the research provides a succinct examination of the spacetime geometry and the configuration of its horizon. Furthermore, we study the…

General Relativity and Quantum Cosmology · Physics 2026-03-17 Weiqiang Yang , Mirzabek Alloqulov , Ahmadjon Abdujabbarov , Bobomurat Ahmedov , Chengxun Yuan , Chen Zhou

We study shadow aspects of superentropic black holes in four dimensions. Using Hamilton-Jacobi formalism, we first get the null geodesic equations. In the celestial coordinate framework relying on fixed positions of observers, we…

High Energy Physics - Theory · Physics 2022-07-27 A. Belhaj , H. Belmahi , M. Benali

In this paper, we derive an exact black hole spacetime metric in the Einstein-Hilbert-Bumblebee (EHB) gravity around global monopole field. We study the horizon, temperature, and the photon sphere of the black hole. Using the null geodesics…

General Relativity and Quantum Cosmology · Physics 2021-12-21 İbrahim Güllü , Ali Övgün

The gravitational field around an astrophysical black hole (BH) is thought to be described by the Kerr spacetime, which is a solution of the Einstein equation. Signatures of binary black hole (BBH) coalescence in gravitational waves (GW)…

General Relativity and Quantum Cosmology · Physics 2024-12-03 Debtroy Das , Swarnim Shashank , Cosimo Bambi

Using backwards ray tracing, we study the shadows of Kerr black holes with scalar hair (KBHsSH). KBHsSH interpolate continuously between Kerr BHs and boson stars (BSs), so we start by investigating the lensing of light due to BSs. Moving…

General Relativity and Quantum Cosmology · Physics 2015-11-25 Pedro V. P. Cunha , Carlos A. R. Herdeiro , Eugen Radu , Helgi F. Runarsson

In this paper, we study the particle dynamics, shadow, and optical appearance of charged black holes (BHs) in bumblebee gravity. Firstly, we find that the Lorentz-violation parameter l and charge parameter Q have opposite effects on the…

General Relativity and Quantum Cosmology · Physics 2025-07-03 Mou Xu , Jianbo Lu , Ruonan Li , Yu Liu , Shu-Min Wu

The Event Horizon Telescope (EHT) image of M87* provides a direct test of strong-field gravity, measuring an angular shadow diameter $\theta_{d}=42\pm 3~\mu\mathrm{as}$ and a circularity deviation $\Delta C\leq 0.1$. Such observations allow…

General Relativity and Quantum Cosmology · Physics 2026-05-13 Kourosh Nozari , Milad Hajebrahimi , Sara Saghafi , G. Mustafa , Emmanuel N. Saridakis

This article deals with the study of some properties of the static and rotating black holes in Kalb-Ramond gravity in four dimensional spacetime. First, we discuss the action of the corresponding theory and the static black hole metric.…

General Relativity and Quantum Cosmology · Physics 2023-10-20 M. Zubair , Muhammad Ali Raza , Eiman Maqsood

The shadow of a rotating black hole with nonvanishing gravitomagnetic charge has been studied. It was shown that in addition to the angular momentum of black hole the gravitomagnetic charge term deforms the shape of the black hole shadow.…

We study the prospects of using the low-redshift and high-redshift black hole shadows as new cosmological standard rulers for measuring cosmological parameters. We show that, using the low-redshift observation of the black hole shadow of…

Cosmology and Nongalactic Astrophysics · Physics 2020-04-28 Jing-Zhao Qi , Xin Zhang

Dark matter (DM), a fundamental cosmic component, motivates the study of its influence on black hole (BH) shadows, especially for spinning BHs confirmed by EHT observations. This work generalizes the Schwarzschild BH surrounded by DM to an…

General Relativity and Quantum Cosmology · Physics 2026-05-26 Haiyuan Feng , Ziqiang Cai , Rong-Jia Yang , Jinjun Zhang

A black hole casts a shadow as an optical appearance because of its strong gravitational field. We study the shadow cast by the five-dimensional Myers-Perry black hole with equal rotation parameters. We demonstrate that the null geodesic…

General Relativity and Quantum Cosmology · Physics 2015-06-22 Uma Papnoi , Farruh Atamurotov , Sushant G. Ghosh , Bobomurat Ahmedov

In this paper, by exploring the photon motion in the region near the Bardeen black hole, the shadow and observation properties of the black hole surrounded by various accretion models are studied. We analyzed the changes in shadow imaging…

High Energy Physics - Theory · Physics 2022-08-17 Ke-Jian He , Sen Guo , Shuang-Cheng Tan , Guo-Ping Li

We analysed the shadow cast by charged rotating black hole (BH) in presence of perfect fluid dark matter (PFDM). We studied the null geodesic equations and obtained the shadow of the charged rotating BH to see the effects of PFDM parameter…

General Relativity and Quantum Cosmology · Physics 2022-01-05 Farruh Atamurotov , Uma Papnoi , Kimet Jusufi

We study the impact of different fluid matter scenarios on the shadow of black holes (BH) and on frequencies of quasinormal modes (QNM) for a black hole subjected to scalar perturbations, with a comparison to the standard Kerr. The analysis…

General Relativity and Quantum Cosmology · Physics 2026-02-10 Reza Pourkhodabakhshi , Jorge G. Russo

We consider the rotating generalization of the Bardeen black hole solution in the presence of cloud of strings (CoS). The parameter space for which the black hole horizon exists is determined. We also study the static limit surface and the…

General Relativity and Quantum Cosmology · Physics 2023-11-01 Bijendra Kumar Vishvakarma , Dharm Veer Singh , Sanjay Siwach

A certain type of matter with anisotropic pressures can add to the Reissner-Nordstr\"om metric a term proportional to a power of the radial coordinate. Using the standard method of separating variables for the Hamilton-Jacobi equation, we…

General Relativity and Quantum Cosmology · Physics 2023-01-30 Javier Badía , Ernesto F. Eiroa

The Event Horizon Telescope (EHT) has imaged the shadow of the supermassive black hole in M87. A library of general relativistic magnetohydrodynamics (GMRHD) models was fit to the observational data, providing constraints on black hole…

High Energy Astrophysical Phenomena · Physics 2021-06-09 Freek Roelofs , Christian M. Fromm , Yosuke Mizuno , Jordy Davelaar , Michael Janssen , Ziri Younsi , Luciano Rezzolla , Heino Falcke

This study probes spacetime solutions within Einstein-Bumblebee gravity, a modified gravitational framework incorporating spontaneous Lorentz symmetry violation through a vector field mechanism. By introducing a cosmological constant into…

General Relativity and Quantum Cosmology · Physics 2025-08-04 Reggie C. Pantig , Shubham Kala , Ali Övgün , Nikko John Leo S. Lobos