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Interior perfect fluid solutions for the Reissner-Nordstrom metric are studied on the basis of a new classification scheme. It specifies which two of the fluid's characteristics are given functions and picks up accordingly one of the three…

General Relativity and Quantum Cosmology · Physics 2007-05-23 B. V. Ivanov

Gravitational collapse of a spherically symmetric homogeneous perfect barotropic fluid with linear as well as polytropic type Equation of State (EoS) has been investigated in the framework of a linear model of $f(R,T)$ gravity. This…

General Relativity and Quantum Cosmology · Physics 2020-05-06 Karim Mosani , Gauranga C. Samanta

In astrophysics, the gravitational stability of a self-gravitating polytropic fluid sphere is an intriguing subject, especially when trying to comprehend the genesis and development of celestial bodies like planets and stars. This stability…

General Relativity and Quantum Cosmology · Physics 2024-07-10 Mohamed S. Aboueisha , A. S. Saad , Mohamed I. Nouh , Tarek M. Kamel , M. M. Beheary , Kamel A. K. Gadallah

We investigate static spherically symmetric perfect fluid models in Newtonian gravity for barotropic equations of state that are asymptotically polytropic at low and high pressures. This is done by casting the equations into a 3-dimensional…

Astrophysics · Physics 2009-11-07 J. Mark Heinzle , Claes Uggla

Thermodynamical stability of fluid spheres is studied in the presence of a cosmological constant, both in the Newtonian limit, as well as in General Relativity. In all cases, an increase of the cosmological constant tends to stabilize the…

General Relativity and Quantum Cosmology · Physics 2013-05-22 Zacharias Roupas

We extend General Relativity by promoting Planck scale and the cosmological constant into integration constants, interpreted as fluxes of $4$-forms hiding in the theory. When we include the charges of the $4$-forms, these `constants' can…

High Energy Physics - Theory · Physics 2022-10-05 Nemanja Kaloper

In this paper, we study the electromagnetic effects on stability of spherically symmetric anisotropic fluid distribution satisfying two polytropic equations of state and construct the corresponding generalized Tolman Oppenheimer Volkoff…

General Relativity and Quantum Cosmology · Physics 2016-11-23 M. Sharif , Sobia Sadiq

The dynamical instability of relativistic polytropic spheres, embedded in a spacetime with a repulsive cosmological constant, is studied in the framework of general relativity. We apply the methods used in our preceding paper to study the…

General Relativity and Quantum Cosmology · Physics 2020-07-22 Camilo Posada , Jan Hladík , Zdenek Stuchlík

We study the general formalism of polytropes in relativistic regime with generalized polytropic equations of state in the vicinity of cylindrical symmetry. We take charged anisotropic fluid distribution of matter with conformally flat…

General Physics · Physics 2016-10-12 M. Azam , S. A. Mardan , I. Noureen , M. A. Rehman

This paper investigates the complexity of a charged static sphere filled with anisotropic matter in the background of energy-momentum squared gravity. For this purpose, we evaluate the modified field and conservation equations to determine…

General Relativity and Quantum Cosmology · Physics 2022-05-19 M. Sharif , Ayesha Anjum

In this work a class of interior solution for Einstein field equations corresponding to a spherically symmetric anisotropic fluid sphere has been obtained under the assumption that the cosmological constant is spatially variable. The…

General Relativity and Quantum Cosmology · Physics 2011-03-07 R. N. Tiwari , Saibal Ray

We consider a static spherically symmetric charged anisotropic fluid source of finite physical radius (\sim 10^{-16} cm) by introducing a scalar variable \Lambda dependent on the radial coordinate r under general relativity. From the…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Saibal Ray , Sumana Bhadra

The main objective of this paper is to investigate the impact of $f(\mathcal{Q},\mathcal{T})$ gravity on the geometry of anisotropic compact stellar objects, where $\mathcal{Q}$ is non-metricity and $\mathcal{T}$ is the trace of the…

General Relativity and Quantum Cosmology · Physics 2024-02-21 M. Zeeshan Gul , M. Sharif , Adeeba Arooj

Interior perfect fluid solutions for the Reissner-Nordstrom metric are studied on the basis of a new classification scheme. General formulas are found in many cases. Explicit new global solutions are given as illustrations. Known solutions…

General Relativity and Quantum Cosmology · Physics 2009-11-07 B. V. Ivanov

Within $R^2$ gravity, we study the linear stability of strongly gravitating spherically symmetric configurations supported by a polytropic fluid. All calculations are carried out in the Jordan frame. It is demonstrated that, as in general…

General Relativity and Quantum Cosmology · Physics 2020-09-29 Vladimir Dzhunushaliev , Vladimir Folomeev

In this article, we provide a pedagogical review of the Tolman-Oppenheimer-Volkoff (TOV) equation and its solutions which describe static, spherically symmetric gaseous stars in general relativity. Our discussion starts with a systematic…

General Relativity and Quantum Cosmology · Physics 2021-06-15 Emmanuel Chavez Nambo , Olivier Sarbach

We examine static perfect fluid spheres in the presence of a cosmological constant. New exact matter solutions are discussed which require the Nariai metric in the vacuum region. We generalize the Einstein static universe such that neither…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Christian G. Boehmer , Gyula Fodor

The original Thomson problem of "spherical crystallography" seeks the ground state of electron shells interacting via the Coulomb potential; however one can also study crystalline ground states of particles interacting with other…

Soft Condensed Matter · Physics 2009-11-11 Mark J. Bowick , Angelo Cacciuto , David R. Nelson , Alex Travesset

We exhibit a simple and explicit formula for the metric of an arbitrary static spherically symmetric perfect fluid spacetime. This class of metrics depends on one freely specifiable monotone non-increasing generating function. We also…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Shahinur Rahman , Matt Visser

We study the general properties of fluid spheres satisfying the heuristic assumption that their areas and proper radius are equal (the Euclidean condition). Dissipative and non-dissipative models are considered. In the latter case, all…

General Relativity and Quantum Cosmology · Physics 2014-11-20 L. Herrera , N. O. Santos