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A new class of analytic charged spherically symmetric black hole solutions, which behave asymptotically as flat or (A)dS spacetimes, is derived for specific classes of $f(R)$ gravity, i.e., $f(R)=R-2\alpha\sqrt{R}$ and…

General Relativity and Quantum Cosmology · Physics 2019-07-18 Gamal G. L. Nashed , Salvatore Capozziello

This thesis is dedicated to the study of symmetries in reduced models of gravity, with some frozen degrees of freedom. We focus on the minisuperspace reduction whith a finite number of degrees of freedom. Minisuperspaces are treated as…

General Relativity and Quantum Cosmology · Physics 2022-11-10 Francesco Sartini

We study the hamiltonian and constraints of spherically symmetric dilaton gravity model. We find the ADM mass of the solution representing the Schwarzchild black hole in thermal equilibrium with the Hawking radiation.

General Relativity and Quantum Cosmology · Physics 2010-11-19 Maja Buric , Voja Radovanovic

We consider a class of spherically symmetric spacetime to obtain some interesting solutions in F(R) gravity without matter field (pure gravity). We investigate the geometry of the solutions and find that there is an essential singularity at…

General Relativity and Quantum Cosmology · Physics 2014-03-03 S. H. Hendi , B. Eslam Panah , C. Corda

In this work we study whether parametrized spherically symmetric black hole solutions in metric theories of gravity can appear to be isospectral when studying perturbations. From a theory agnostic point of view, the test scalar field wave…

General Relativity and Quantum Cosmology · Physics 2019-09-04 Sebastian H. Völkel , Kostas D. Kokkotas

We propose a new $\bar{\mu}$-scheme Hamiltonian effective dynamics in the spherical symmetric sector of Loop Quantum Gravity (LQG). The effective dynamics is generally covariant as derived from a covariant Lagrangian. The Lagrangian belongs…

General Relativity and Quantum Cosmology · Physics 2022-12-12 Muxin Han , Hongguang Liu

The possibility of spherically symmetric solutions in bi-metric theory of gravity is examined. It is shown that two possible black hole type solutions exists in the model. Spherically symmetric solution of general theory of relativity is…

General Relativity and Quantum Cosmology · Physics 2014-03-28 Anoop Narayanan P E , P K Suresh

We show that under certain technical assumptions, including the existence of a constant mean curvature (CMC) slice and strict positivity of the scalar field, general relativity conformally coupled to a scalar field can be quantised on a…

General Relativity and Quantum Cosmology · Physics 2013-04-25 Norbert Bodendorfer , Alexander Stottmeister , Andreas Thurn

Black holes are among the most fascinating objects populating our universe. Their characteristic features, encompassing spacetime singularities, event horizons, and black hole thermodynamics, provide a rich testing ground for quantum…

High Energy Physics - Theory · Physics 2016-02-23 Frank Saueressig , Natalia Alkofer , Giulio D'Odorico , Francesca Vidotto

We derive the full spacetime metric of a generalized uncertainty-inspired quantum black hole. We examine a previous model of the interior in this approach and show that extending its metric to the full spacetime leads to serious issues in…

General Relativity and Quantum Cosmology · Physics 2025-01-22 Federica Fragomeno , Douglas M. Gingrich , Samantha Hergott , Saeed Rastgoo , Evan Vienneau

Exact static spherically symmetric charged black holes in four dimensions are presented. One of them has only electric charge and another electric and magnetic charges. In these solutions the metric is asymptotically flat, has two horizons,…

General Relativity and Quantum Cosmology · Physics 2009-11-11 E. Kyriakopoulos

We elaborate on the Ashtekar's formalism for spherically symmetric midisuperspaces and, for loop quantization, propound a new quantization scheme which yields a graph-preserving Hamiltonian constraint operator and by which one can impose…

General Relativity and Quantum Cosmology · Physics 2013-01-28 Dah-Wei Chiou , Wei-Tou Ni , Alf Tang

We study static spherically symmetric solutions of Einstein gravity plus an action polynomial in the Ricci scalar, $R$, of arbitrary degree, $n$, in arbitrary dimension, $D$. The global properties of all such solutions are derived by…

High Energy Physics - Theory · Physics 2010-11-19 S. Mignemi , D. L. Wiltshire

Numerical codes based on a direct implementation of the standard ADM formulation of Einstein's equations have generally failed to provide long-term stable and convergent evolutions of black hole spacetimes when excision is used to remove…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Bernard Kelly , Pablo Laguna , Keith Lockitch , Jorge Pullin , Erik Schnetter , Deirdre Shoemaker , Manuel Tiglio

The Einstein/Maxwell equations reduce in the stationary and axially symmetric case to a harmonic map with prescribed singularities phi: R^3\Sigma -> H^2_C, where Sigma is a subset of the axis of symmetry, and H^2_C is the complex hyperbolic…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Gilbert Weinstein

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

We study the asymptotic behavior of the spherically symmetric solutions of the system obtained from the dimensional reduction of the six-dimensional Einstein- Gauss-Bonnet action. We show that in general the scalar field that parametrizes…

General Relativity and Quantum Cosmology · Physics 2008-11-26 S. Mignemi

We study quantum corrections for the Schwarzshild black hole by considering it as a vacuum solution of a 2D dilaton gravity theory obtained by spherical reduction of 4D gravity coupled with matter. We find perturbatively the vacuum solution…

General Relativity and Quantum Cosmology · Physics 2009-01-16 Maja Buric , Voja Radovanovic , Aleksandar Mikovic

The effective action of $N=2$, $d=4$ supergravity is shown to acquire no quantum corrections in background metrics admitting super-covariantly constant spinors. In particular, these metrics include the Robinson-Bertotti metric (product of…

High Energy Physics - Theory · Physics 2009-10-22 Renata Kallosh

An exact spherically symmetric black hole solution of a recently proposed noncommutative gravity theory based on star products and twists is constructed. This is the first nontrivial exact solution of that theory. The resulting…

High Energy Physics - Theory · Physics 2009-06-16 Peter Schupp , Sergey Solodukhin