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In this paper we study anisotropic spherical polytropes within the framework of general relativity. Using the anisotropic Tolman-Oppenheimer-Volkov (TOV) equations, we explore the relativistic anisotropic Lane-Emden equations. We find how…

General Relativity and Quantum Cosmology · Physics 2016-07-20 F. Shojai , M. Kohandel , A. Stepanian

We study a generalized Thomson problem that appears in several condensed matter settings: identical point-charge particles can penetrate inside a homogeneously charged sphere, with global electro-neutrality. The emphasis is on scaling laws…

Soft Condensed Matter · Physics 2015-05-27 A. D. Chepelianskii , F. Closa , E. Raphael , E. Trizac

A spherically symmetric hydrodynamic stellar core collapse under gravity is time-dependent and may become unstable once disturbed. Specifically for a homologously collapse of stellar core characterized by a polytropic exponent \Gamma=4/3,…

Solar and Stellar Astrophysics · Physics 2013-10-10 Yu-Qing Lou , Biao Lian

We explore local consequences of a non-zero cosmological constant on astrophysical structures. We find that the effects are not only sensitive to the density of the configurations but also to the geometry. For non-homogeneous…

Astrophysics · Physics 2010-12-13 Marek Nowakowski , Andres Balaguera-Antolinez

Based on the assertion that the cosmological constant problem is essentially a quantum gravity problem, the framework which addresses the cosmological constant problem should also bear a picture for the ``quantum space-time''. In this talk…

High Energy Physics - Phenomenology · Physics 2009-10-07 M. M. Sheikh-Jabbari

Charged stars have the potential of becoming charged black holes or even naked singularities. It is presented a set of numerical solutions of the Tolman-Oppenheimer-Volkov equations that represents spherical charged compact stars in…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Cristian R. Ghezzi

We consider scalar-tensor gravity with nonminimal derivative coupling and Born-Infeld electromagnetic field which is minimally coupled to gravity. Since cosmological constant is taken into account it allowed us not only derive static black…

High Energy Physics - Theory · Physics 2020-05-22 M. M. Stetsko

As an alternative gravity model we consider an extended Einstein-Maxwell gravity containing a gauge invariance property. Extension is assumed to be addition of a directional coupling between spatial electromagnetic fields with the Ricci…

General Relativity and Quantum Cosmology · Physics 2024-01-08 Hossein Ghaffarnejad , Leyla Naderi

The transport coefficients of a dilute gas of inelastic hard spheres immersed in a molecular gas are determined. We assume that the number density of the granular gas is much smaller than that of the surrounding molecular gas, so that the…

Soft Condensed Matter · Physics 2022-06-07 Rubén Gómez González , Vicente Garzó

The resolution of the problem of cosmological singularity in the framework of gauge theories of gravitation is discussed. Generalized cosmological Friedmann equations for homogeneous isotropic models filled by interacting scalar fields and…

General Relativity and Quantum Cosmology · Physics 2017-08-23 Albert V. Minkevich

We obtain bounds on the stability of various self-gravitating astrophysical objects using a new measure of shape complexity known as configurational entropy. We apply the method to Newtonian polytropes, neutron stars with an…

General Relativity and Quantum Cosmology · Physics 2016-07-06 Marcelo Gleiser , Nan Jiang

We introduce a class of states characterized by proposed conditions of homogeneity and isotropy in loop quantum gravity and construct concrete examples given by Bell-network states on a special class of homogeneous graphs. Such states…

General Relativity and Quantum Cosmology · Physics 2023-03-29 Bekir Baytas , Nelson Yokomizo

An ensemble of cosmological models based on generalized BF-theory is constructed where the role of vacuum (zero-level) coupling constants is played by topologically invariant rational intersection forms (cosmological-constant matrices) of…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Vladimir N. Efremov , Nikolai V. Mitskievich , Alfonso M. Hernandez Magdaleno , Ramona Serrano Bautista

We complete previous investigations on the thermodynamics of self-gravitating systems by studying the grand canonical, grand microcanonical and isobaric ensembles. We also discuss the stability of polytropic spheres in the light of a…

Astrophysics · Physics 2009-11-07 P. H. Chavanis

We investigate, in the framework of (2+1) dimensional gravity, stationary, rotationally symmetric gravitational sources of the perfect fluid type, embedded in a space of arbitrary cosmological constant. We show that the matching conditions…

General Relativity and Quantum Cosmology · Physics 2009-10-31 M. Lubo , M. Rooman , Ph. Spindel

We study the thermodynamic properties of a static electrically charged spherical thin shell in $d$ dimensions by imposing the first law of thermodynamics on the shell. The shell is at radius $R$, inside it the spacetime is Minkowski, and…

General Relativity and Quantum Cosmology · Physics 2022-11-28 Tiago V. Fernandes , José P. S. Lemos

This paper analyzes the stability of the closed Einstein static universe by using linear homogeneous perturbations in the framework of energy-momentum squared gravity. This newly developed proposal resolves the primordial singularity and…

General Relativity and Quantum Cosmology · Physics 2021-08-25 M. Sharif , M. Zeeshan Gul

A variational framework is developed to examine the equilibrium states of a semi-flexible polymer that is constrained to lie on a fixed surface. As an application the confinement of a closed polymer loop of fixed length $2\pi R$ within a…

Soft Condensed Matter · Physics 2012-02-17 Jemal Guven , Pablo Vázquez-Montejo

The dynamics of charged particles moving around a Kerr-Newman black hole surrounded by cloud strings, quintessence and electromagnetic field is integrable due to the presence of a fourth constant of motion like the Carter constant. The…

General Relativity and Quantum Cosmology · Physics 2022-06-22 Wenfu Cao , Wenfang Liu , Xin Wu

The equations describing the adiabatic, small radial oscillations of general relativistic stars are generalized to include the effects of a cosmological constant. The generalized eigenvalue equation for the normal modes is used to study the…

General Relativity and Quantum Cosmology · Physics 2007-05-23 C. G. Boehmer , T. Harko