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Recently the small value of the cosmological constant and its ability to accelerate the expansion of the Universe is of great interest. We discuss the possibility of forming of anisotropic compact stars from this cosmological constant as…

General Relativity and Quantum Cosmology · Physics 2015-06-04 Sk. Monowar Hossein , Farook Rahaman , Jayanta Naskar , Mehedi Kalam , Saibal Ray

We analyze the possibility of global anisotropy of the universe. We consider an altered Friedmann Lemaitre Robertson Walker metric in which there are different scale factors along the three different axes of space. We construct the…

Cosmology and Nongalactic Astrophysics · Physics 2025-05-06 Mark P. Hertzberg , Abraham Loeb

We systematically study late-time tails of scalar waves propagating in neutron star spacetimes. We consider uniform density neutron stars, for which the background spacetime is analytic and the compaction of the star can be varied…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Vasiliki Pavlidou , Konstantinos Tassis , Thomas W. Baumgarte , Stuart L. Shapiro

Polytropic stars are useful tools for learning about stellar structure without the complexity of comprehensive stellar models. These models rely on a certain power-law correlation between the star's pressure and density. This paper proposes…

General Relativity and Quantum Cosmology · Physics 2024-07-19 Akashdip Karmakar , Ujjal Debnath , Pramit Rej

A new class of solutions describing the composition of compact stars has been proposed, assuming that the fluid distribution inside the star is anisotropic. This is achieved by assuming the appropriate metric potential and then solving…

General Physics · Physics 2020-03-11 D. M. Pandya , B. Thakore , R. Goti , J. P. Rank , S. Shah

Unitarity of evolution in gravitational collapses implies existence of macroscopic stable horizonless objects. With such objects in mind, we study the effects of anisotropy of pressures on the stability of stars. We consider stars in four…

High Energy Physics - Theory · Physics 2015-10-05 S. Kalyana Rama

For spherically symmetric relativistic perfect fluid models, the well-known Buchdahl inequality provides the bound $2 M/R \leq 8/9$, where $R$ denotes the surface radius and $M$ the total mass of a solution. By assuming that the ratio…

General Relativity and Quantum Cosmology · Physics 2007-08-27 J. Mark Heinzle

This manuscript explores the compact geometries by employing Karmarkar condition with the charged anisotropic source of matter distribution. For this purpose, we consider an explicit model by indulging $\mathrm{g}_{rr}$ metric potential…

General Relativity and Quantum Cosmology · Physics 2021-05-05 M. Farasat Shamir , G. Mustafa , Mushtaq Ahmad

A random mixture of two isotropic dielectric materials, one composed of oriented spheroidal particles of relative permittivity $\epsilon_a$ and the other composed of oriented spheroidal particles of relative permittivity $\epsilon_b$, was…

Optics · Physics 2015-06-19 Tom G. Mackay

This paper reports a study on the formation and physical characteristics of compacts stars in AdS spacetime within the framework of Bose-Einstein Condensate. Considering a Bose-Einstein condensate background at zero temperature this study…

General Relativity and Quantum Cosmology · Physics 2026-05-20 Samprity Das , Aroonkumar Beesham , Surajit Chattopadhyay

New exact interior solutions to the Einstein field equations for anisotropic spheres are found. We utilise a procedure that necessitates a choice for the energy density and the radial pressure. This class contains the constant density model…

General Relativity and Quantum Cosmology · Physics 2009-11-11 M. Chaisi , S. D. Maharaj

Upper limits for the mass-radius ratio are derived for arbitrary general relativistic matter distributions in the presence of a cosmological constant. General restrictions for the red shift and total energy (including the gravitational…

General Relativity and Quantum Cosmology · Physics 2012-08-27 M. K. Mak , Peter N. Dobson, , T. Harko

We explore the long-term evolution of the anisotropy in the velocity space of star clusters starting with different structural and kinematical properties. We show that the evolution of the radial anisotropy strength and its radial variation…

Astrophysics of Galaxies · Physics 2015-12-09 Maria Tiongco , Enrico Vesperini , Anna Lisa Varri

In this work we analyze the observational properties of relativistic fluid spheres when orbited by isotropically emitting sources, known as hot spots. We consider fluid star configurations in four different regimes of compacticity, from the…

General Relativity and Quantum Cosmology · Physics 2024-03-11 Hanna Liis Tamm , João Luís Rosa

This paper is the first in a sequence of three devoted to the formulation of a theory of self-gravitating anisotropic fluids in both Newtonian and relativistic gravity. In this first paper we set the stage, place our work in the context of…

General Relativity and Quantum Cosmology · Physics 2024-06-06 Tom Cadogan , Eric Poisson

We investigate the structure and radial oscillations of anisotropic compact stars composed of dark energy, using the vanishing complexity factor formalism within general relativity. This novel approach establishes a direct link between the…

General Relativity and Quantum Cosmology · Physics 2024-07-25 G. Panotopoulos , A. Rincon , I. Lopes

In this investigation we examine the astrophysical consequences of the influence of pressure anisotropy on the physical properties of observed pulsars within the background of $f(Q,T)$ gravity by choosing a specific form $f(Q, T)=\psi_1\, Q…

General Relativity and Quantum Cosmology · Physics 2025-10-08 S. K. Maurya , Abdul Aziz , Ksh. Newton Singh , G. Mustafa , Y. Sekhmani , Saibal Ray

We investigate the stability of self-gravitating spherically symmetric anisotropic spheres under radial perturbations. We consider both the Newtonian and the full general-relativistic perturbation treatment. In the general-relativistic…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Krsna Dev , Marcelo Gleiser

In this work some families of relativistic anisotropic charged fluid spheres have been obtained by solving Einstein-Maxwell field equations with preferred form of one of the metric potentials, a suitable forms of electric charge…

General Relativity and Quantum Cosmology · Physics 2014-09-02 Mohammad Hassan Murad , Saba Fatema

We derive upper and lower bounds on the mass-radius ratio of stable compact objects in extended gravity theories, in which modifications of the gravitational dynamics via-{\' a}-vis standard general relativity are described by an effective…

General Relativity and Quantum Cosmology · Physics 2016-10-05 Piyabut Burikham , Tiberiu Harko , Matthew J. Lake
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