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In this paper, a new class of string and holographic dark energy (HDE) cosmological model in the context of the $f(R)$ theory of gravity using the Kasner metric is considered. The exact solution of the field equations is obtained using the…

General Relativity and Quantum Cosmology · Physics 2024-10-22 S. P. Hatkar , D. P. Tadas , A. S. Agrawal , S. D. Katore

We construct a new family of regular black hole solutions supported by the novel Letelier-Alencar string cloud and regularized through a rational Dagum-type distribution. The regulator smooths the matter profile and ensures finite curvature…

To ask a question about a black hole in quantum gravity, one must restrict initial or boundary data to ensure that a black hole is actually present. For two-dimensional dilaton gravity, and probably a much wider class of theories, I show…

High Energy Physics - Theory · Physics 2010-04-28 S. Carlip

Our research aims to probe the anisotropic matter field around black holes using black hole perturbation theory. Black holes in the universe are usually surrounded by matter or fields, and it is important to study the perturbation and the…

General Relativity and Quantum Cosmology · Physics 2025-03-12 Sagar J C , Karthik R , Katheek Hegde , K. M. Ajith , Shreyas Punacha , A. Naveena Kumara

We present exact spherically symmetric null dust solutions in the third order Lovelock gravity with a string cloud background in arbitrary $N$ dimensions,. This represents radiating black holes and generalizes the well known Vaidya solution…

General Relativity and Quantum Cosmology · Physics 2015-06-23 Sushant G. Ghosh , Sunil D. Maharaj

In this study, we investigate the geodesic motion of massless particles -- specifically photons -- in the spacetime of a charged anti-de Sitter (AdS) black hole (BH) surrounded by a cloud of strings (CoS) within the framework of Kalb-Ramond…

General Relativity and Quantum Cosmology · Physics 2026-01-21 Faizuddin Ahmed , Ahmad Al-Badawi , İzzet Sakallı

Some black hole mimickers, as well as black strings and other higher-dimensional spacetimes, exhibit stable light rings-regions where light or high-frequency gravitational waves can be trapped. In these regions, linear perturbations decay…

General Relativity and Quantum Cosmology · Physics 2025-06-11 Jaime Redondo-Yuste , Alejandro Cárdenas-Avendaño

Here, we explore the effect of the cloud of strings (CoS) on the gravitational waveforms of extreme mass ratio inspirals (EMRIs). The EMRI system consists of a supermassive black hole (BH) and a compact stellar mass object moving around it.…

General Relativity and Quantum Cosmology · Physics 2025-12-16 Mirzabek Alloqulov , Ahmadjon Abdujabbarov , Bobomurat Ahmedov , Chengxun Yuan

We report the existence of unstable, s-wave modes, for black strings in Gauss-Bonnet theory (which is quadratic in the curvature) in seven dimensions. This theory admits analytic uniform black strings that in the transverse section are…

High Energy Physics - Theory · Physics 2015-05-08 Alex Giacomini , Julio Oliva , Aldo Vera

We obtain the solution corresponding to a static and spherically symmetric black hole with a cloud of strings (Letelier spacetime) immersed in a quintessential fluid. We discuss some aspects of its thermodynamics. We also present a…

General Relativity and Quantum Cosmology · Physics 2019-03-08 Marco M. Dias e Costa , J. M. Toledo , V. B. Bezerra

We construct a charged Bardeen black hole (BH) surrounded by perfect fluid dark matter (PFDM) and coupled to a cloud of strings (CS). The metric function combines the magnetic monopole charge from nonlinear electrodynamics, the PFDM…

General Relativity and Quantum Cosmology · Physics 2026-02-04 Faizuddin Ahmed , Ahmad Al-Badawi , İzzet Sakallı

A class of nonstationary spacetimes is obtained by means of a conformal transformation of the Schwarzschild metric, where the conformal factor $a(t)$ is an arbitrary function of the time coordinate only. We investigate several situations…

General Relativity and Quantum Cosmology · Physics 2017-05-05 Marina M. C. Mello , Alan Maciel , Vilson T. Zanchin

We give an exact description of the steady flow of a black string into a planar horizon. The event horizon is out of equilibrium and provides a simple, exact instance of a `flowing black funnel' in any dimension D>=5. It is also an…

High Energy Physics - Theory · Physics 2022-03-07 Roberto Emparan , Marina Martinez

We derive the solution for a spherically symmetric string cloud configuration in a d-dimensional spacetime in the framework of f(R) theories of gravity. We also analyze some thermodynamic properties of the joint black hole - cloud of…

General Relativity and Quantum Cosmology · Physics 2018-06-12 J. P. Morais Graça , Iarley P. Lobo , I. G. Salako

It is expected that the astrophysical black holes are surrounded by a luminous accretion flow that is a necessary ingredient for imaging a black hole. In this paper, we study the influence of quintessence dark energy on the shadow images of…

General Relativity and Quantum Cosmology · Physics 2023-12-27 Malihe Heydari-Fard

The last three years have again seen new exciting developments in the area of higher dimensional black objects. For black objects with noncompact higher dimensions, the solution space was exlored further within the blackfold approach and…

General Relativity and Quantum Cosmology · Physics 2016-04-04 Burkhard Kleihaus , Jutta Kunz

Spacetime quantization predicts the existence of minimal length and time-interval. Within 5-dimensional Schwarzschild-like black string background, the tunneling of scalar particles, fermions and massive bosons are first studied together in…

High Energy Physics - Theory · Physics 2016-09-09 Xiang-Qian Li

We study the black hole thermodynamics in the presence of a string cloud matter distribution, considering a work term due to a variable cosmological "constant" in arbitrary dimensions. Then, we explore the criticality of the system and the…

General Relativity and Quantum Cosmology · Physics 2018-10-19 J. P. Morais Graça , Iarley P. Lobo , Valdir B. Bezerra , H. Moradpour

We examine the geometry near the event horizon of a family of black string solutions with traveling waves. It has previously been shown that the metric is continuous there. Contrary to expectations, we find that the geometry is not smooth,…

High Energy Physics - Theory · Physics 2016-08-24 Gary T. Horowitz , Haisong Yang

Cosmic strings are topological defects thought to have formed early in the life of the universe. If such objects exist, a study of their interaction with black holes is of interest. The equations of motion of a cosmic string have the form…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Jean-Pierre De Villiers