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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 $f(R,T)$…

广义相对论与量子宇宙学 · 物理学 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…

广义相对论与量子宇宙学 · 物理学 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…

综合物理 · 物理学 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…

天体物理学 · 物理学 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)…

广义相对论与量子宇宙学 · 物理学 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.…

综合物理 · 物理学 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…

广义相对论与量子宇宙学 · 物理学 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…

广义相对论与量子宇宙学 · 物理学 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…

广义相对论与量子宇宙学 · 物理学 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…

广义相对论与量子宇宙学 · 物理学 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…

广义相对论与量子宇宙学 · 物理学 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…

广义相对论与量子宇宙学 · 物理学 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…

广义相对论与量子宇宙学 · 物理学 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…

广义相对论与量子宇宙学 · 物理学 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…

广义相对论与量子宇宙学 · 物理学 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…

广义相对论与量子宇宙学 · 物理学 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…

广义相对论与量子宇宙学 · 物理学 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…

广义相对论与量子宇宙学 · 物理学 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…

广义相对论与量子宇宙学 · 物理学 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…

高能物理 - 理论 · 物理学 2019-09-04 Hyeong-Chan Kim , Youngone Lee