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200 papers

We study the existence and radial stability of static, spherically symmetric thin shells separating two Schwarzschild--de Sitter spacetimes with parameters $(m_\pm,\Lambda_\pm)$. Using the Israel junction formalism and a linear barotropic…

General Relativity and Quantum Cosmology · Physics 2026-02-26 Dimitrios Efstratiou , Evangelos Achilleas Paraskevas , Leandros Perivolaropoulos

In this paper we investigate the gravitational vacuum stars which called gravastars in the non-minimally coupled models with electromagnetic and gravitational fields. We consider two non-minimal models and find the corresponding spherically…

General Relativity and Quantum Cosmology · Physics 2021-11-18 Özcan Sert , Muzaffer Adak

The physical properties of a (3+1)-D gravastar in the context of massive gravity are discussed in this work. In present investigation, the field equations have been solved for a static, uncharged sphere in order to achieve the gravastar…

General Relativity and Quantum Cosmology · Physics 2024-04-10 Piyali Bhar

In this article, we assume that a cold charged perfect fluid is constructing a spherical relativistic star. Our purpose is the investigation of the dynamical properties of its exterior geometry, through simulating the geodesic motion of a…

General Relativity and Quantum Cosmology · Physics 2015-03-19 Mohsen Fathi

A new final state of gravitational collapse is proposed. By extending the concept of Bose-Einstein condensation to gravitational systems, a cold, dark, compact object with an interior de Sitter condensate $p_{_V} = -\rho_{_V}$ and an…

General Relativity and Quantum Cosmology · Physics 2009-10-19 Pawel O. Mazur , Emil Mottola

A new model is proposed to a collapsing star consisting of an anisotropic fluid with bulk viscosity, radial heat flow and outgoing radiation. In a previous paper one of us has introduced a function time dependent into the $g_{rr}$, besides…

General Relativity and Quantum Cosmology · Physics 2013-01-14 G. Pinheiro , R. Chan

We study some quantum mechanical aspects of dynamical black holes where the Vaidya metric is used as a model representing evaporating black holes. It is shown that in this model the Wheeler-DeWitt equation is solvable in whole region of…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Ichiro Oda

We prove a theorem that characterizes a large family of non-static solutions to Einstein equations in $N$-dimensional space-time, representing, in general, spherically symmetric Type II fluid. It is shown that the best known Vaidya-based…

General Relativity and Quantum Cosmology · Physics 2008-11-26 S. G. Ghosh , A. K. Dawood

We construct a gravastar configuration within the Shtanov-Sahni (SS) braneworld scenario, characterized by a timelike extra dimension and negative brane tension. Unlike classical black holes, which inevitably culminate in central curvature…

General Relativity and Quantum Cosmology · Physics 2026-03-25 Shounak Ghosh , Rikpratik Sengupta , Kazuharu Bamba

Gravastars have been considered as a serious alternative to black holes in the past couple of decades. Stable models of gravastar have been constructed in many of the alternate gravity models besides standard General Relativity (GR). The…

General Relativity and Quantum Cosmology · Physics 2020-07-15 Rikpratik Sengupta , Shounak Ghosh , Saibal Ray , B. Mishra , S. K. Tripathy

Conditions for the fragmentation of expanding shells due to gravitational instability are discussed. The self-similar analytical solution is compared with the results of 3-dimensional computer simulations for the expansion into homogeneous…

Astrophysics · Physics 2007-05-23 S. Ehlerova , J. Palous , Ch. Theis , G. Hensler

Gravastars, hypothetic astrophysical objects, consisting of a dark energy condensate surrounded by a strongly correlated thin shell of anisotropic matter, have been proposed as an alternative to the standard black hole picture of general…

General Relativity and Quantum Cosmology · Physics 2009-10-06 Tiberiu Harko , Zoltán Kovács , Francisco S. N. Lobo

We establish a generic, fully-relativistic formalism to study gravitational-wave emission by extreme-mass-ratio systems in spherically-symmetric, non-vacuum black-hole spacetimes. The potential applications to astrophysical setups range…

General Relativity and Quantum Cosmology · Physics 2022-12-21 Vitor Cardoso , Kyriakos Destounis , Francisco Duque , Rodrigo Panosso Macedo , Andrea Maselli

In this paper, we show that it is possible to have pure quantum gravastar solution to the quantum improved Einstein equations. Such an object is essentially a gravastar in which the thin layer of matter is replaced by quantum effects. The…

General Relativity and Quantum Cosmology · Physics 2022-08-30 Raihaneh Moti , Ali Shojai

We demonstrate steady-state, mirrorless superradiance in a cold vapor pumped by weak optical fields. Beyond a critical pump intensity of 1 mW/cm$^2$, the vapor spontaneously transforms into a spatially self-organized state: a density…

Atomic Physics · Physics 2015-06-04 Joel A. Greenberg , Daniel J. Gauthier

We summarize the general formalism describing surface flows in three-dimensional space in a form which is suitable for various astrophysical applications. We then apply the formalism to the analysis of non-radial perturbations of…

General Relativity and Quantum Cosmology · Physics 2009-10-31 J. Bicak , B. G. Schmidt

We demonstrate the existence of static stable spherical fluid shells in the Schwarzschild-Rindler-anti-de Sitter (SRAdS) spacetime where $ds^2 = f(r)dt^{2} -\frac{dr^{2}}{f(r)}-r^{2}(d\theta ^2 +\sin ^2 \theta d\phi ^2)$ with $f(r) = 1…

General Relativity and Quantum Cosmology · Physics 2020-11-11 G. Alestas , G. V. Kraniotis , L. Perivolaropoulos

We investigate an infinitesimally thin cylindrical shell composed of counter-rotating dust particles. This system was studied by Apostolatos and Thorne in terms of the C-energy for a bounded domain. In this paper, we reanalyze this system…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Ken-ichi Nakao , Daisuke Ida , Yasunari Kurita

The paradox of a free falling radiating charged particle in a gravitational field, is a well-known fascinating conceptual challenge that involves classical electrodynamics and general relativity. We discuss this paradox considering the…

General Relativity and Quantum Cosmology · Physics 2018-06-13 Fabrizio Tamburini , Mariafelicia De Laurentis , Ignazio Licata

The aim of this work is to analyze the dynamical behavior of relativistic infinite axial-symmetric shells with flat interior and a radiation filled curved exterior spacetimes. It will be proven, by the use of conservation equations of…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Burak Himmetoglu