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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

The aim of this paper is to investigate the stable/unstable regimes of the non-static anisotropic filamentary stellar models in the framework of $f(R,T,R_{\mu\nu}T^{\mu\nu})$ gravity. We construct the field equations and conservation laws…

General Physics · Physics 2017-06-22 Z. Yousaf , M. Zaeem-ul-Haq Bhatti , Ume Farwa

We study the dynamical stability of self-gravitating systems in presence of anisotropy. In particular, we introduce a stability criterion, in terms of the adiabatic local index, that generalizes the stability condition $<\gamma> \geq 4/3$…

General Relativity and Quantum Cosmology · Physics 2022-06-29 Giuseppe Alberti

We study the dynamical instability of anisotropic collapsing cylinder with the expansion-free condition, which generates vacuum cavity within fluid distribution. The perturbation scheme is applied to distinguish Newtonian, post-Newtonian…

General Relativity and Quantum Cosmology · Physics 2015-06-16 M. Sharif , M. Azam

The stability criteria for the generalized Brans-Dicke cosmology in a spatially flat, homogeneous and isotropic cosmological model is discussed in the presence of a perfect fluid. The generalization comes through the channel that the…

General Relativity and Quantum Cosmology · Physics 2017-04-05 Nandan Roy , Narayan Banerjee

We derive dynamical equations to describe a single 3-brane containing fluid matter and a scalar field coupling to the dilaton and the gravitational field in a five dimensional bulk. First, we show that a scalar field or an arbitrary fluid…

High Energy Physics - Theory · Physics 2012-10-23 Timon Boehm , Ruth Durrer , Carsten van de Bruck

This manuscript is devoted to study the combined effect of a viable model, f(R) = R + \alpha R^n, and electromagnetic field on the instability range of gravitational collapse. We assume charged anisotropic fluid that dissipate energy via…

General Relativity and Quantum Cosmology · Physics 2014-02-03 H. Rizwana Kausar , Ifra Noureen

We present results about the effect of the use of a stiffer equation of state, namely the ideal-fluid $\Gamma=2.75$ ones, on the dynamical bar-mode instability in rapidly rotating polytropic models of neutron stars in full General…

General Relativity and Quantum Cosmology · Physics 2014-07-16 Roberto De Pietri , Alessandra Feo , Luca Franci , Frank Löffler

We perform a non-radial adiabatic perturbation analysis on homologous conventional polytropic stellar core collapses. The core collapse features a polytropic exponent $\Gamma=4/3$ relativistic gas under self-gravity of spherical symmetry…

High Energy Astrophysical Phenomena · Physics 2015-05-14 Yi Cao , Yu-Qing Lou

We assume cylindrically symmetric stars which begin collapsing by dissipating energy in the form of heat flux. We wish to study the effects of Carroll-Duvvuri-Trodden-Turner (CDTT) model, $f(R)=R+\sigma\frac{\mu^4}{R}$, on the range of…

General Relativity and Quantum Cosmology · Physics 2015-06-12 Hafiza Rizwana Kausar

A re-investigation of the gravothermal catastrophe is presented. By means of a linear perturbation analysis, we study the dynamical stability of a spherical self-gravitating isothermal fluid of finite volume and find that the conditions for…

Astrophysics of Galaxies · Physics 2015-06-12 M. C. Sormani , G. Bertin

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

In this paper, we explore instability regions of non-static axial reflection symmetric spacetime with anisotropic source in the interior. We impose linear perturbation on the Einstein field equations and dynamical equations to establish the…

General Physics · Physics 2015-12-16 M. Sharif , M. Zaeem Ul Haq Bhatti

This paper is devoted to study the stability/instability of the expansionfree self gravitating source in the framework of Einstein Gauss-Bonnet gravity. The source has been taken as Tolman-Bondi model which is homogenous in nature. The…

General Relativity and Quantum Cosmology · Physics 2015-04-22 G. Abbas , S. Sarwar

By the end of the evaluation of this research artifact, readers would be able to describe the effect of conducted plasma on evolution of stellar objects. In this script, we have analyzed the stability of charged cylindrically symmetric…

General Relativity and Quantum Cosmology · Physics 2019-10-28 Muhammad Asad Saeed , Ifra Noureen

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

We investigate a puzzle in the recent thermodynamics of scalar-tensor gravity, in which general relativity is a zero-temperature state of equilibrium and scalar-tensor gravity is the non-equilibrium configuration of an effective dissipative…

General Relativity and Quantum Cosmology · Physics 2022-05-18 Valerio Faraoni , Théo B. Françonnet

We study the implications of $R^n$ extension of Starobinsky model on dynamical instability of Vorticity-free axially symmetric gravitating body. The matter distribution is considered to be anisotropic for which modified field equations are…

General Relativity and Quantum Cosmology · Physics 2015-04-13 Ifra Noureen , Abdul Aziz Bhatti , M. Zubair

A global O$(2,2)$ symmetry is found in the Brans-Dicke theory of gravity when the dilaton is coupled to axion and moduli fields. The symmetry is broken if a cosmological constant is introduced. Within the class of spatially homogeneous…

General Relativity and Quantum Cosmology · Physics 2016-08-31 James E. Lidsey

We discovered an oscillatory instability in a system of inelastically colliding hard spheres, driven by two opposite "thermal" walls at zero gravity. The instability, predicted by a linear stability analysis of the equations of granular…

Soft Condensed Matter · Physics 2009-11-10 Evgeniy Khain , Baruch Meerson