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We consider the quantization of the complete extension of the Schwarzschild space-time using spherically symmetric loop quantum gravity. We find an exact solution corresponding to the semi-classical theory. The singularity is eliminated but…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Rodolfo Gambini , Jorge Pullin

In this paper, we consider Einstein-Hilbert gravity in the presence of cosmological constant with cylindrical symmetry to introduce the black hole solution of this model. Here, we solve the Einstein's vacuum field equation, and then we…

General Relativity and Quantum Cosmology · Physics 2023-04-24 Mehdi Sadeghi , Ramin Anvari Asl , Mohammad Shamseh

New general spherically symmetric solutions have been derived with a cosmological "constant" \Lambda as a source. This \Lambda field is not constant but it satisfies the properties of the asymptotically safe gravity at the ultraviolet fixed…

High Energy Physics - Theory · Physics 2023-09-26 Georgios Kofinas , Vasilios Zarikas

We construct exact, entropy satisfying shock wave solutions of the Einstein equations for a perfect fluid which extend the Oppeheimer-Snyder (OS) model to the case of non-zero pressure, {\it inside the Black Hole}. These solutions put forth…

Mathematical Physics · Physics 2007-05-23 Joel Smoller , Blake Temple

From time to time, different observations suggest that Einstein's theory of general relativity (GR) may not be the ultimate theory of gravity. Various researchers have suggested that the $f(R)$ theory of gravity is the best alternative to…

General Relativity and Quantum Cosmology · Physics 2023-01-27 Surajit Kalita , Banibrata Mukhopadhyay

We investigate non-linear, spherically symmetric solutions to the coupled system of a quintessence field and Einstein gravity. In the presence of a scalar potential, we find regular solutions that to an outside observer very closely…

Astrophysics · Physics 2009-06-23 Timm Krueger , Matthias Neubert , Christof Wetterich

Two of the most fundamental problems at the nexus of Einstein's classical General Relativity (GR) and Quantum Field Theory (QFT) are: (1) complete gravitational collapse, presumed in classical GR to lead to a Black Hole (BH) horizon and…

General Relativity and Quantum Cosmology · Physics 2022-06-02 Emil Mottola

We derive noncommutative Einstein equations for abelian twists and their solutions in consistently symmetry reduced sectors, corresponding to twisted FRW cosmology and Schwarzschild black holes. While some of these solutions must be…

High Energy Physics - Theory · Physics 2009-10-20 Thorsten Ohl , Alexander Schenkel

Einsteinian cubic gravity is a higher-order gravitational theory in which the linearized field equations of motion match Einstein's equations on a maximally symmetric background. This theory allows the existence of a static and spherically…

General Relativity and Quantum Cosmology · Physics 2023-07-06 Antonio De Felice , Shinji Tsujikawa

A toy model of Einstein gravity with a Gauss-Bonnet classically "entropic" term mimicking a quantum correction is considered. The static black hole solution due to Tomozawa is found and generalized with the inclusion of non trivial horizon…

General Relativity and Quantum Cosmology · Physics 2013-10-15 Guido Cognola , Ratbay Myrzakulov , Lorenzo Sebastiani , Sergio Zerbini

In this paper, we derive a novel Schwarzschild-like black hole (BH) solution describing a static and asymptotically flat BH surrounded by a dark matter (DM) halo with a Dehnen-type density distribution in the surrounding environment. We…

General Relativity and Quantum Cosmology · Physics 2024-11-05 Ahmad Al-Badawi , Sanjar Shaymatov , Yassine Sekhmani

Recent observation shows that general relativity (GR) is not valid in the strong regime. $\mathit{f(R)}$ gravity where $\mathit{R}$ is the Ricci scalar, is regarded to be one of good candidates able to cure the anomalies appeared in the…

General Relativity and Quantum Cosmology · Physics 2021-07-01 G. G. L. Nashed , S. Nojiri

We study static spherically symmetric solutions to the vacuum field equations of quadratic gravity in the presence of a cosmological constant $\Lambda$. Motivated by the trace no-hair theorem, we assume the Ricci scalar to be constant…

General Relativity and Quantum Cosmology · Physics 2021-03-26 Vojtech Pravda , Alena Pravdova , Jiri Podolsky , Robert Svarc

We investigate how a spherically symmetric fluid modifies the Schwarzschild vacuum solution when there is no exchange of energy-momentum between the fluid and the central source of the Schwarzschild metric. This system is described by means…

General Relativity and Quantum Cosmology · Physics 2018-11-26 J Ovalle , R Casadio , R da Rocha , A Sotomayor , Z Stuchlik

Recently Horava proposed a renormalizable gravity theory in four dimensions which reduces to Einstein gravity with a non-vanishing cosmological constant in IR but with improved UV behaviors. Here, I study an IR modification which breaks…

High Energy Physics - Theory · Physics 2009-10-02 Mu-in Park

Exploring the characterization of singular black hole spacetimes, we study the relation between energy density, curvature invariants, and geodesic completeness using a quadratic $f(R)$ gravity theory coupled to an anisotropic fluid. Working…

High Energy Physics - Theory · Physics 2017-04-05 Cecilia Bejarano , Gonzalo J. Olmo , Diego Rubiera-Garcia

While non-rotating black-hole solutions are well known in Einstein--\ae{}ther gravity, no axisymmetric solutions endowed with Killing horizons have been so far found outside of the slowly rotating limit. Here we show that the Kerr spacetime…

General Relativity and Quantum Cosmology · Physics 2024-04-22 Edgardo Franzin , Stefano Liberati , Jacopo Mazza

Generalization of a known theorem to generate static, spherically symmetric black-hole solutions in higher dimensional Lovelock gravity is presented. Particular limits, such as Gauss-Bonnet (GB) and/or Einstein-Hilbert (EH) in any dimension…

General Relativity and Quantum Cosmology · Physics 2010-01-06 S. Habib Mazharimousavi , O. Gurtug , M. Halilsoy

In a recent paper[1], it has been shown that, there cannot be any rotating (Kerr) Black Hole (BH) with finite mass in order that the generic properties associated with the symmetries of stationary axisymmetric Einstein equations are obeyed,…

Astrophysics · Physics 2016-08-30 Abhas Mitra

In the context of $f(R)$ gravity theories, the issue of finding static and spherically symmetric black hole solutions is addressed. Two approaches to study the existence of such solutions are considered: first, constant curvature solutions,…

General Relativity and Quantum Cosmology · Physics 2014-11-20 Alvaro de la Cruz-Dombriz , Antonio Dobado , Antonio L. Maroto