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We studied a new class of interior solutions that are singular-free and useful for describing anisotropic compact star objects with spherically symmetric matter distribution. We have considered metric potential selecting B_0^2…

General Relativity and Quantum Cosmology · Physics 2023-10-19 B. S. Ratanpal , Rinkal Patel

We have investigated the stability of a set of non-rotating anisotropic spherical models with a phase-space distribution function of the Osipkov-Merritt type. The velocity distribution in these models is isotropic near the center and…

Astrophysics · Physics 2009-10-30 Andres Meza , Nelson Zamorano

[Abridged] Recently we have found that a family of models of partially relaxed, anisotropic stellar systems, inspired earlier by studies of incomplete violent relaxation, exhibits some interesting thermodynamic properties. Here we present a…

Astrophysics · Physics 2009-11-10 M. Trenti , G. Bertin

Non-radial oscillation modes of a neutron star possess valuable information about its internal structure and nuclear physics. Starting from the quadrupolar order, such modes under general relativity are known as quasi-normal modes since…

General Relativity and Quantum Cosmology · Physics 2024-11-22 Shu Yan Lau , Siddarth Ajith , Victor Guedes , Kent Yagi

Various solutions of the kinetic equation for the equilibrium of a gravitating sphere of uniform density with a quadratic gravitational potential and a linear dependence of gravitational force on radius are examined. New analytic solutions…

Astrophysics of Galaxies · Physics 2021-07-21 G. S. Bisnovatyi-Kogan

We investigate a compact spherically symmetric relativistic body with anisotropic particle pressure profiles. The distribution possesses characteristics relevant to modeling compact stars within the framework of general relativity. For this…

General Relativity and Quantum Cosmology · Physics 2018-02-28 S. K. Maurya , Ayan Banerjee , Sudan Hansraj

In present work, we have studied a new stellar distribution model with spherically symmetric matter and an uncharged isotropic distribution in general relativity. In this model, we have considered a particular metric potential. The model is…

General Relativity and Quantum Cosmology · Physics 2021-09-03 Amit Kumar Prasad , Jitendra Kumar , Ashok Kumar

In this paper, the gravitational field equations for static spherically symmetric perfect fluid models with a polytropic equation of state, $p=k\rho^{1+1/n}$, are recast into two complementary 3-dimensional {\it regular} systems of ordinary…

General Relativity and Quantum Cosmology · Physics 2009-10-31 U. S. Nilsson , C. Uggla

We present a class of new relativistic solutions with anisotropic fluid for compact stars in hydrostatic equilibrium. The interior space-time geometry considered here for compact objects are described by parameters namely, $\lambda$, $k$,…

General Relativity and Quantum Cosmology · Physics 2016-03-25 Bikash Chandra Paul , Rumi Deb

We study the oscillations and stability of self-gravitating cylindrically symmetric fluid systems and collisionless systems. This is done by studying small perturbations to the equilibrium system and finding the normal modes, using methods…

Cosmology and Nongalactic Astrophysics · Physics 2014-01-15 Patrick C. Breysse , Marc Kamionkowski , Andrew Benson

In several previous investigations we presented models of triaxial stellar systems, both cuspy and non cuspy, that were highly stable and harboured large fractions of chaotic orbits. All our models had been obtained through cold collapses…

Astrophysics of Galaxies · Physics 2015-06-18 D. D. Carpintero , J. C. Muzzio , H. D. Navone

Equilibrium states in galactic dynamics can be described as stationary solutions of the Vlasov-Poisson system, which is the non-relativistic case, or of the Vlasov-Einstein system, which is the relativistic case. To obtain spherically…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Gerhard Rein , Alan D. Rendall

The so-called ``symplectic method'' is used for studying the linear stability of a self-gravitating collisionless stellar system, in which the particles are also submitted to an external potential. The system is steady and spherically…

Astrophysics · Physics 2015-06-24 J. Perez , J-J Aly

We present preliminary results on a new family of distribution functions that are able to generate axisymmetric, truncated (i.e., finite size) stellar dynamical models characterized by toroidal shapes. The relevant distribution functions…

Astrophysics · Physics 2009-11-10 L. Ciotti , G. Bertin , P. Londrillo

Assuming the separable augmented density, it is always possible to construct a distribution function of a spherical population with any given density and anisotropy. We consider under what conditions the distribution constructed as such is…

Cosmology and Nongalactic Astrophysics · Physics 2012-04-19 J. An , E. Van Hese , M. Baes

We propose a relativistic model for quintessence stars with the combination of an anisotropic pressure corresponding to normal matter and a quintessence dark energy having a characteristic parameter {\omega}q such that -1 <{\omega}q < -…

General Relativity and Quantum Cosmology · Physics 2015-06-16 Mehedi Kalam , Farook Rahaman , Sajahan Molla , Sk. Monowar Hossein

In this paper, we have introduced new viable solutions of Einstein-Maxwell field equations by incorporating the features of anisotropic matter distribution in the realm of General theory of Relativity ($GR$). For this procurement, we have…

General Relativity and Quantum Cosmology · Physics 2023-03-29 H. Nazar , M. Azam , G. Abbas , R. Ahmed , R. Naeem

We consider spherically symmetric spacetimes sourced by a fluid with pressure anisotropy in the radial direction. We use gauge-invariant perturbation theory to study the stability of this class of spacetimes under axial perturbations. We…

General Relativity and Quantum Cosmology · Physics 2014-07-23 Bhavesh Khamesra , V Suneeta

Non-axisymmetric oscillations of differentially rotating stars are studied using both slow rotation and Cowling approximation. The equilibrium stellar models are relativistic polytropes where differential rotation is described by the…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Andrea Passamonti , Adamantios Stavridis , Kostas Kokkotas

This paper presents two families of phase-space distribution functions (DFs) that generate scale-free spheroidal mass densities in scale-free spherical potentials. The `case I' DFs are anisotropic generalizations of the flattened f(E,L_z)…

Astrophysics · Physics 2015-06-24 Jos H. J. de Bruijne , Roeland P. van der Marel , P. Tim de Zeeuw