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We investigate irregularity factors for a self-gravitating spherical star evolving in the presence of imperfect fluid. We explore the gravitational field equations and the dynamical equations with the systematic construction in $f(R,T)$…

General Relativity and Quantum Cosmology · Physics 2016-06-29 Z. Yousaf , Kazuharu Bamba , M. Zaeem ul Haq Bhatti

In this paper, we formulate two exact charged solutions to the field equations by extending the domain of existing anisotropic models with the help of minimal gravitational decoupling in $f(\mathbb{R},\mathbb{T})$ theory. For this, the…

General Relativity and Quantum Cosmology · Physics 2023-12-07 M. Sharif , Tayyab Naseer

We present an algorithm to generalize a plethora of well-known solutions to Einstein field equations describing spherically symmetric relativistic fluid spheres by relaxing the pressure isotropy condition on the system. By suitably fixing…

General Physics · Physics 2018-02-14 S. Thirukkanesh , F. C. Ragel , Ranjan Sharma , Shyam Das

Static spherically symmetric perfect fluid solutions are studied in metric $f(R)$ theories of gravity. We show that pressure and density do not uniquely determine $f(R)$ ie. given a matter distribution and an equation state, one cannot…

Astrophysics · Physics 2008-11-26 T. Multamaki , I. Vilja

We consider static spherically symmetric self-gravitating configurations of the perfect fluid within the framework of the torsion-based extended theory of gravity. In particular, we use the covariant formulation of $f(T)$ gravity with $f(T)…

General Relativity and Quantum Cosmology · Physics 2018-10-03 Sasa Ilijic , Marko Sossich

We consider a modified gravity theory, $f(R)=R+\alpha R^n-\frac{\mu^4}{R^m}$, in the metric formulation and analyze the contribution of electromagnetic field on the range of dynamical instability of a star filled with anisotropic matter.…

General Physics · Physics 2015-10-22 H. Rizwana Kausar , Ifra Noureen , M. Umair Shahzad

The present work investigates the gravitational collapse of a perfect fluid in $f(R)$ gravity models. For a general $f(R)$ theory, it is shown analytically that a collapse is quite possible. The singularity formed as a result of the…

General Relativity and Quantum Cosmology · Physics 2016-03-30 Soumya Chakrabarti , Narayan Banerjee

This paper is about the $n+2$-dimensional gravitational contraction of inhomogeneous fluid without heat flux in the framework of $f(R)$ metric theory of gravity. Matching conditions for two regions of a star has been derived by using the…

General Relativity and Quantum Cosmology · Physics 2017-08-02 G. Abbas , M. S. Khan , Zahid Ahmad , M. Zubair

In this paper, we have continued the work of Herrera \emph{et al.} \cite{herrera2012dynamical} in $f(G)$ gravitational theory. For this purpose, a spherically symmetric fluid exhibiting locally anisotropic pressure along with the energy…

General Relativity and Quantum Cosmology · Physics 2020-05-19 M. Z. Bhatti , Z. Yousaf , A. Khadim

Ivanov pointed out substantial analytical difficulties associated with self-gravitating, static, isotropic fluid spheres when pressure explicitly depends on matter density. Simplification achieved with the introduction of electric charge…

General Relativity and Quantum Cosmology · Physics 2014-11-20 Victor Varela , Farook Rahaman , Saibal Ray , Koushik Chakraborty , Mehedi Kalam

This paper aims to formulate certain scalar factors associated with matter variables for self-gravitating non-static cylindrical geometry by considering a standard model $\mathcal{R}+\zeta\mathcal{Q}$ of…

General Relativity and Quantum Cosmology · Physics 2023-11-02 M. Sharif , T. Naseer

In this paper, we study the effects of modification of gravity on the problem of dynamical instability of the spherical relativistic anisotropic interiors. We have considered non-zero influence of expansion scalar throughout during the…

General Relativity and Quantum Cosmology · Physics 2018-07-17 Z. Yousaf , Kazuharu Bamba , M. Z. Bhatti , U. Farwa

In this work we shall investigate the cosmological dynamical system of $f(R)$ gravity, by constructing it in such a way so that it is rendered autonomous. We shall study the vacuum $f(R)$ gravity case, but also the case that matter and…

General Relativity and Quantum Cosmology · Physics 2018-01-17 S. D. Odintsov , V. K. Oikonomou

We investigate some exact static cylindrically symmetric solutions for a perfect fluid in the metric $f(R)$ theory of gravity. For this purpose, three different families of solutions are explored. We evaluate energy density, pressure, Ricci…

General Relativity and Quantum Cosmology · Physics 2015-06-12 M. Sharif , Sadia Arif

This paper formulates some new exact solutions to the field equations by means of minimal gravitational decoupling in the context of $f(\mathbb{R},\mathbb{T})$ gravity. For this purpose, we consider anisotropic spherical matter distribution…

General Relativity and Quantum Cosmology · Physics 2022-12-14 M. Sharif , Tayyab Naseer

In this paper, we analyze stability regions of a non-static restricted class of axially symmetric spacetime with anisotropic matter distribution. We consider $f(R)=R+{\epsilon}R^2$ model and assume hydrostatic equilibrium of the axial…

General Relativity and Quantum Cosmology · Physics 2014-11-19 M. Sharif , Z. Yousaf

The selfgravity of an infalling gas can alter significantly the accretion of gases. In the case of spherically symmetric steady flows of polytropic perfect fluids the mass accretion rate achieves maximal value when the mass of the fluid is…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Bogusz Kinasiewicz , Patryk Mach , Edward Malec

This paper discusses the gravitational collapse of dynamical self-gravitating fluid distribution in $f(\mathcal{R},\mathcal{T},\mathcal{Q})$ gravity, where $\mathcal{Q}=\mathcal{R}_{\varphi\vartheta}\mathcal{T}^{\varphi\vartheta}$. In this…

General Relativity and Quantum Cosmology · Physics 2024-01-11 M. Sharif , Tayyab Naseer

The fluid models mentioned in the title are classified. All characteristics of the fluid are expressed through a master potential, satisfying an ordinary second order differential equation. Different constraints are imposed on this core of…

General Relativity and Quantum Cosmology · Physics 2015-05-27 B. V. Ivanov

We examine the entropy of self-gravitating anisotropic matter confined to a box in the context of generalrelativity. The configuration of self-gravitating matter is spherically symmetric, but has anisotropic pressure of which angular part…

High Energy Physics - Theory · Physics 2019-09-04 Hyeong-Chan Kim , Youngone Lee