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We investigate the strong gravitational lensing and shadow properties of the black hole in the context of bumblebee gravity, characterized by a global monopole charge $\kappa\eta^2$ and a Lorentz symmetry breaking parameter $\gamma$. We…

General Relativity and Quantum Cosmology · Physics 2026-01-01 Bijendra Kumar Vishvakarma , Shubham Kala

Recent observations of the supermassive black holes M87* and Sgr A* by the Event Horizon Telescope (EHT) have opened new avenues for testing gravity theories through black hole shadow observables. These observations offer a means to…

General Relativity and Quantum Cosmology · Physics 2025-05-05 Mohsen Fathi , Yassine Sekhmani

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

Massive scalar charges are ubiquitous in extensions to General Relativity and the Standard Model in particle physics. We describe spectral methods which can accurately construct the spacetime of rotating black holes with dimensionless spin…

General Relativity and Quantum Cosmology · Physics 2026-05-28 Adrian Ka-Wai Chung

One of the most important and actual issues in relativistic astrophysics is testing gravity theories and obtaining constraint values for the parameters of black holes using observational data. In this research, we aimed to explore the…

General Relativity and Quantum Cosmology · Physics 2024-06-14 Saeed Ullah Khan , Javlon Rayimbaev , Furkat Sarikulov , Ozodbek Abdurakhmonov

In this article, we present the thermodynamic and shadow properties of rotating black holes with global monopole charge. The angular diameter of Sgr A$^{*}$ black hole is 48.7 $\pm$ 7 $\mu as$, which is 8 $kps$ far away having a mass of $M…

General Relativity and Quantum Cosmology · Physics 2025-06-04 Balendra Pratap Singh , Md Sabir Ali

In \cite{Estrada:2024uuu}, a link between gravitational tension (GT) and energy density via the Kretschmann scalar (KS) was proposed to construct regular black holes (RBHs) in Pure Lovelock (PL) gravity. However, including a negative…

General Relativity and Quantum Cosmology · Physics 2025-10-15 Rodrigo Aros , Milko Estrada , Bastian Astudillo , R. Prado-Fuentes

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

In this paper, the shadows cast by Einstein-Maxwell-Dilaton-Axion black hole and naked singularity are studied. The shadow of a rotating black hole is found to be a dark zone covered by a deformed circle. For a fixed value of the spin $a$,…

General Relativity and Quantum Cosmology · Physics 2013-12-03 Shao-Wen Wei , Yu-Xiao Liu

Using an improved version of the Newman-Janis algorithm, we obtain metrics of rotating black holes for a set of extended gravity theories that extend general relativity in different ways: the Horndeski model, the bumblebee model, the…

General Relativity and Quantum Cosmology · Physics 2025-03-24 Stanislav Alexeyev , Oleg Zenin , Artem Baiderin

Weak gravitational lensing by black holes and wormholes in the context of massive gravity (Bebronne and Tinyakov 2009) theory is studied. The particular solution examined is characterized by two integration constants, the mass $M$ and an…

General Relativity and Quantum Cosmology · Physics 2018-05-01 Kimet Jusufi , Nayan Sarkar , Farook Rahaman , Ayan Banerjee , Sudan Hansraj

In this work, we investigate the optical properties of a new black hole recently obtained from the Dunkl operator formalism involving a relevant parameter denoted by $\xi$. Concretely, we first investigate the shadows, the Lyapunov…

General Relativity and Quantum Cosmology · Physics 2024-12-13 N. Askour , A. Belhaj , L. Chakhchi , H. El Moumni , K. Masmar

The first images of black hole shadows open new possibilities to constrain modern extended gravity theories. We present the method of shadow background calculation for black hole solutions in the form of Taylor series where $g_{11} = -…

General Relativity and Quantum Cosmology · Physics 2022-09-07 V. Prokopov , S. Alexeyev , O. Zenin

Poincar\'e Gauge's theory of gravity is the most noteworthy alternative extension of general relativity that has a correspondence between spin and spacetime geometry. In this paper, we use Reissner-Nordstrom-de Sitter and anti-de Sitter…

General Relativity and Quantum Cosmology · Physics 2022-12-23 Reggie C. Pantig , Ali Övgün

In this paper, we investigate the properties of black holes within the framework of multi-fractional theories of gravity, focusing on the effects of q-derivatives and weighted derivatives. These modifications, which introduce…

General Relativity and Quantum Cosmology · Physics 2025-06-03 Reggie C. Pantig

We consider rational nonlinear electrodynamics with the Lagrangian ${\cal L} = -{\cal F}/(1+2\beta{\cal F})$ (${\cal F}=(1/4)F_{\mu\nu}F^{\mu\nu}$ is the Lorentz-invariant), proposed in [63], coupled to General Relativity. The effective…

General Relativity and Quantum Cosmology · Physics 2020-12-02 S. I. Kruglov

Shadows cast by the rotating black hole in perfect fluid matter are studied using analytical method. We consider three kinds of matter with standard equation of state in Cosmology: $-1/3$ (dark matter), 0 (dust) and $1/3$ (radiation). The…

General Relativity and Quantum Cosmology · Physics 2018-10-31 Zhaoyi Xu , Xian Hou , Jiancheng Wang

We employ Bozza's method to calculate the deflection angle of light in the presence of the strong gravitational field generated by an improved Schwarzschild-like black hole whose metric, regular throughout the entire spacetime, was derived…

General Relativity and Quantum Cosmology · Physics 2025-10-22 Javier Chagoya , I. Díaz-Saldaña , Benito Rodríguez , Wilfredo Yunpanqui

We propose a new method to determine the physical parameters of Kerr black holes (namely, specific angular momentum $a$, inclination angle $i$, and distance $D$ from an observer) only from the shadow's information such as the size and…

General Relativity and Quantum Cosmology · Physics 2024-02-20 Kenta Hioki , Umpei Miyamoto

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