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We study the gravitational collapse and formation of the Kerr black hole from the rotating progenitor star. We follow the evolution of black hole spin, coupled with its increasing mass. We study the effect of different level of rotation…

High Energy Astrophysical Phenomena · Physics 2020-12-08 Agnieszka Janiuk , Dominika Król

We introduce the notion of a local shadow for a black hole and determine its shape for the particular case of a distorted Schwarzschild black hole. Considering the lowest-order even and odd multiple moments, we compute the relation between…

General Relativity and Quantum Cosmology · Physics 2015-05-11 Shohreh Abdolrahimi , Robert B. Mann , Christos Tzounis

Zhang have obtained recently a twisted rotating black hole metric, which is a vacuum solution in four-dimensional Einstein gravity. This black hole solution has a rotation parameter, but without the total angular moment. Here, we have…

General Relativity and Quantum Cosmology · Physics 2016-10-21 Songbai Chen , Jiliang Jing

Recent observational data from the Event Horizon Telescope (EHT) collaboration provide convincing realistic evidence for the existence of black hole rotation. From a phenomenological perspective, a recently proposed stable rotating regular…

General Relativity and Quantum Cosmology · Physics 2025-01-15 Chen-Hao Xie , Yu Zhang , Qi Sun , Qi-Quan Li , Peng-Fei Duan

We have developed a methodology to test the age-old cosmic censorship hypothesis in Kerr geometry. We have shown that the Kerr black hole can be overspun by particles captured from the innermost stable circular orbit. However, it appears…

General Relativity and Quantum Cosmology · Physics 2023-03-21 Dishari Malakar , K Rajesh Nayak

We consider the evaporation of rotating micro black holes produced in highly energetic particle collisions, taking into account the polarization due to the coupling between the spin of the emitted particles and the angular momentum of the…

High Energy Physics - Phenomenology · Physics 2015-05-13 Antonino Flachi , Misao Sasaki , Takahiro Tanaka

Real astronomical objects possess spin, yet deriving exact solutions for rotating black holes within gravitational theories is a formidable challenge. To understand the shadow of rotating black holes in Lorentz-violating spacetimes induced…

General Relativity and Quantum Cosmology · Physics 2025-08-04 Wentao Liu , Di Wu , Jieci Wang

Within 5-10 years, submillimeter VLBI facilities will be hopefully able to image the "shadow" of SgrA$^*$. When a black hole is surrounded by an optically thin emitting medium, the boundary of the shadow corresponds to the apparent photon…

General Relativity and Quantum Cosmology · Physics 2017-12-19 Cosimo Bambi

Cosmic expansion is expected to influence on the size of black hole shadow observed by comoving observer. Except the simplest case of Schwarzschild black hole in de Sitter universe, analytical approach for calculation of shadow size in…

General Relativity and Quantum Cosmology · Physics 2018-10-24 Gennady S. Bisnovatyi-Kogan , Oleg Yu. Tsupko

Due to its large number of symmetries the Schwarzschild Black Hole can be described by a specific two-dimensional dilaton gravity model. After reviewing classical, semi-classical and quantum properties and a brief discussion of virtual…

General Relativity and Quantum Cosmology · Physics 2007-05-23 D. Grumiller

Cosmic expansion influences the angular size of black hole shadow. The most general way to describe a black hole embedded into an expanding universe is to use the McVittie metric. So far, the exact analytical solution for the shadow size in…

General Relativity and Quantum Cosmology · Physics 2020-08-05 Oleg Yu. Tsupko , Gennady S. Bisnovatyi-Kogan

The recent time witnessed a surge of interest in strong gravitational lensing by black holes is due to the Event Horizon Telescope (EHT) results, which suggest comparing the black hole lensing in both general relativity and heterotic string…

General Relativity and Quantum Cosmology · Physics 2021-03-25 Sushant G. Ghosh , Rahul Kumar , Shafqat Ul Islam

We introduce a novel formalism to investigate the role of the spin angular momentum of astrophysical black holes in influencing the behaviour of low angular momentum general relativistic accretion. We propose a metric independent analysis…

In this article, we considered the strong field approximation of nonlinear electrodynamics black hole and constructed its rotating counterpart by applying the modified Newman-Janis algorithm. The corresponding metric function in the strong…

General Relativity and Quantum Cosmology · Physics 2022-11-23 M. Zubair , Muhammad Ali Raza , Ghulam Abbas

The specific angular momentum of a Kerr black hole must not be larger than its mass. The observational confirmation of this bound which we call a Kerr bound directly suggests the existence of a black hole. In order to investigate…

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

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

The exact metric of a moving Kerr black hole with an arbitrary constant velocity is derived in Kerr-Schild coordinates. We then calculate the null equatorial gravitational deflection caused by a radially moving Kerr source up to the second…

General Relativity and Quantum Cosmology · Physics 2021-08-11 Weijun Li , Zhongwen Feng , Xia Zhou , Xueling Mu , Guansheng He

Simulated images of a black hole surrounded by optically thin emission typically display two main features: a central brightness depression and a narrow, bright "photon ring" consisting of strongly lensed images superposed on top of the…

High Energy Astrophysical Phenomena · Physics 2021-09-08 Andrew Chael , Michael D. Johnson , Alexandru Lupsasca

When an accretion flow extends to the event horizon, their intersection defines the contour of the inner shadow. However, the morphological evolution of this critical feature remains largely unexplored within a torn accretion disk system, a…

General Relativity and Quantum Cosmology · Physics 2026-04-28 Shiyang Hu , Dan Li , Chen Deng , Kejian He

This work introduces a novel formalism to investigate the role of the spin of astrophysical black holes in determining the behaviour of matter falling onto such accretors. Equations describing the general relativistic hydrodynamic accretion…

High Energy Astrophysical Phenomena · Physics 2009-02-25 Paramita Barai , Ipsita Chakraborty , Tapas K Das , Paul J Wiita