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Supermassive black holes at the center of each galaxy may be surrounded by dark matter. Such dark matter admits a spike structure and vanishes at a certain distance from the black hole. This dark matter will impact the spacetime near the…

General Relativity and Quantum Cosmology · Physics 2023-08-02 Yuqian Zhao , Bing Sun , Kai Lin , Zhoujian Cao

We find new explicit solutions describing closed strings spinning with equal angular momentum in two independent planes in the $AdS_5$ black hole spacetime. These are $2n$ folded strings in the radial direction and also winding $m$ times…

High Energy Physics - Theory · Physics 2011-03-28 A. L. Larsen

Wormholes are exotic compact objects characterized by the absence of essential singularities and horizons, acting as slender bridges linking two distinct regions of spacetime. Despite their theoretical significance, they remain however…

General Relativity and Quantum Cosmology · Physics 2025-02-25 Ciro De Simone , Vittorio De Falco , Salvatore Capozziello

A distinct visual signature occurs in black holes that are surrounded by optically thin and geometrically thick emission regions. This signature is a sharp-edged dip in brightness that is coincident with the black-hole shadow, which is the…

High Energy Astrophysical Phenomena · Physics 2021-11-03 Thomas Bronzwaer , Heino Falcke

Shadows of black holes surrounded by an optically thin emitting medium have been extensively discussed in the literature. The Hioki-Maeda algorithm is a simple recipe to characterize the shape of these shadows and determine the parameters…

High Energy Astrophysical Phenomena · Physics 2015-12-04 Lingyun Yang , Zilong Li

In this paper we study the qualitative features induces by corrections to GR coming from String Theory, on the shadows of rotating black holes. We deal with the slowly rotating black hole solutions up to order $\mathcal{O}(a^3)$, to first…

General Relativity and Quantum Cosmology · Physics 2024-06-26 F. Agurto-Sepúlveda , J. Oliva , M. Oyarzo , D. R. G Schleicher

We study optical phenomena related to appearance of Keplerian accretion discs orbiting Kerr superspinars predicted by the string theory. The superspinar exterior is described by the standard Kerr naked singularity geometry breaking the…

General Relativity and Quantum Cosmology · Physics 2015-03-17 Zdenek Stuchlik , Jan Schee

A "temporal analogue" of the standard Poynting-Robertson effect is analyzed as induced by a dust of particles (instead of a gas of photons) surrounding a Schwarzschild black hole. Test particles inside this cloud undergo acceleration…

General Relativity and Quantum Cosmology · Physics 2018-08-20 Donato Bini , Andrea Geralico

It is reported that massive scalar fields can form bound states around Kerr black holes [C. Herdeiro, and E. Radu, Phys. Rev. Lett. 112, 221101 (2014)]. These bound states are called scalar clouds, which have a real frequency…

General Relativity and Quantum Cosmology · Physics 2015-04-21 Ran Li , Junkun Zhao , Xinghua Wu , Yanming 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

This paper discusses the gravitational scattering of a straight, infinitely long test cosmic string by a black hole. We present numerical results that probe the two-dimensional parameter space of impact parameter and initial velocity and…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Jean-Pierre De Villiers , Valeri Frolov

Astrophysical objects like black holes are usually surrounded by matter in the form of accretion disks or jets of matter. These astrophysical scenarios are expected to introduce novel phenomenology in the scattering of particles and fields.…

General Relativity and Quantum Cosmology · Physics 2025-12-05 Leonardo K. S. Furuta , Renan B. Magalhães , Haroldo C. D. Lima Junior , Luís C. B. Crispino

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

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

This work explores the shadow of a black hole within the framework of $F(R)$-ModMax gravity coupled with a cloud of strings. The Einstein field equations are solved for a nonlinear ModMax electromagnetic source in the context of $F(R)$…

General Relativity and Quantum Cosmology · Physics 2025-10-28 Ahmad Al-Badawi

The evaporation of a large mass black hole can be described throughout most of its lifetime by a low-energy effective theory defined on a suitably chosen set of smooth spacelike hypersurfaces. The conventional argument for information loss…

High Energy Physics - Theory · Physics 2009-10-07 David A. Lowe , Joseph Polchinski , Leonard Susskind , Larus Thorlacius , John Uglum

We discuss basic features of the model of spinning particle based on the Kerr solution. It contains a very nontrivial {\it real} stringy structure consisting of the Kerr circular string and an axial stringy system. We consider also the…

High Energy Physics - Theory · Physics 2009-11-10 Alexander Burinskii

The presence of a bright "photon ring" surrounding a dark "black hole shadow" has been discussed as an important feature of the observational appearance of emission originating near a black hole. We clarify the meaning and relevance of…

High Energy Astrophysical Phenomena · Physics 2019-07-17 Samuel E. Gralla , Daniel E. Holz , Robert M. Wald

Black hole superradiance, which only relies on gravitational interactions, can provide a powerful probe of the existence of ultralight bosons that are weakly coupled to ordinary matter. However, as a boson cloud grows through superradiance,…

High Energy Physics - Phenomenology · Physics 2022-10-04 William E. East

Light bending by the strong gravity around the black hole will form the so-called black hole shadow, the shape of which can shed light on the structure of the near-horizon geometry to possibly reveal novel physics of strong gravity and…

General Relativity and Quantum Cosmology · Physics 2022-09-28 Feng-Li Lin , Avani Patel , Hung-Yi Pu