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We derive a Tolman-Oppenheimer-Volkoff equation in neutron star systems within the modified $f(T, \mathcal{T})$-gravity class of models using a perturbative approach. In our approach $f(T, \mathcal{T})$-gravity is considered to be a static…

General Relativity and Quantum Cosmology · Physics 2017-05-08 Mark Pace , Jackson Levi Said

We study relativistic stars in the context of scalar tensor theories of gravity that try to account for the observed cosmic acceleration and satisfy the local gravity constraints via the chameleon mechanism. More specifically, we consider…

General Relativity and Quantum Cosmology · Physics 2015-03-13 E. Babichev , D. Langlois

We study the magnetic braking and viscous damping of differential rotation in incompressible, uniform density stars in general relativity. Differentially rotating stars can support significantly more mass in equilibrium than nonrotating or…

Astrophysics · Physics 2016-08-30 Yuk Tung Liu , Stuart L. Shapiro

Thermal evolution of neutron stars is studied in the $f(R)=R+\alpha R^{2}$ theory of gravity. We first describe the equations of stellar structure and evolution for a spherically symmetric spacetime plus a perfect fluid at rest. We then…

General Relativity and Quantum Cosmology · Physics 2023-06-08 Martín Nava-Callejas , Dany Page , Mikhail V. Beznogov

We model a compact radiant star that undergoes gravitational collapse from a certain initial static configuration until it becomes a black hole. The star consists of a fluid with anisotropy in pressures, bulk viscosity, in addition to the…

General Relativity and Quantum Cosmology · Physics 2023-04-26 A. C. Mesquita , M. F. A. da Silva

We construct the first dynamically stable ergostars (equilibrium neutron stars that contain an ergoregion) for a compressible, causal equation of state. We demonstrate their stability by evolving both strict and perturbed equilibrium…

General Relativity and Quantum Cosmology · Physics 2019-12-11 Antonios Tsokaros , Milton Ruiz , Lunan Sun , Stuart L. Shapiro , Kōji Uryū

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

In the context of linear $f(\mathcal{R},T)=\mathcal{R}+\chi T$ gravity, where $\mathcal{R}$ is the Ricci scalar, $T$ is the trace of the energy-momentum tensor, and $\chi$ is a dimensionless parameter, we have obtained exact analytical and…

General Relativity and Quantum Cosmology · Physics 2023-01-30 Thomas D. Pappas , Camilo Posada , Zdeněk Stuchlík

We present an analytic formulation for the equilibrium gas density profile of early-type galaxies that explicitly includes the contribution of stars in the gravitational potential. We build a realistic model for an isolated elliptical…

Cosmology and Nongalactic Astrophysics · Physics 2012-04-10 Pedro R. Capelo , Priyamvada Natarajan , Paolo S. Coppi

We provide the modified TOV equations for the hydrostatic equilibrium of charged compact stars within the metric $f(R)$ gravitational background. We adopt the MIT bag model EoS for the dense matter and assume a charge distribution where the…

General Relativity and Quantum Cosmology · Physics 2022-09-23 Juan M. Z. Pretel , José D. V. Arbañil , Sergio B. Duarte , Sergio E. Jorás , Ribamar R. R. Reis

Scalar-tensor~(ST) theories of gravity are natural phenomenological extensions to general relativity. Although these theories are severely constrained both by solar system experiments and by binary pulsar observations, a large set of ST…

General Relativity and Quantum Cosmology · Physics 2016-02-10 Carlos Palenzuela , Steve Liebling

The aim of this paper is to introduce a new modified gravity theory named as $f(\mathcal{G},T)$ gravity ($\mathcal{G}$ and $T$ are the Gauss-Bonnet invariant and trace of the energy-momentum tensor, respectively) and investigate energy…

General Relativity and Quantum Cosmology · Physics 2016-12-21 M. Sharif , Ayesha Ikram

We investigate the effect of a strong magnetic field on the structure of neutron stars in a model with perturbative $f(R)$ gravity. The effect of an interior strong magnetic field of about $10^{17 \sim 18}$ G on the equation of state is…

High Energy Astrophysical Phenomena · Physics 2015-06-15 Myung-Ki Cheoun , Cemsinan Deliduman , Can Güngör , Vildan Keleş , C. Y. Ryu , Toshitaka Kajino , Grant J. Mathews

The basic objective of this investigation is to explore the impact of a novel gravitational modification, specifically, the $f(\mathcal{G}, \mathbf{T}^2)$ (where $\mathbf{T}^2 \equiv T_{\alpha\beta}T^{\alpha\beta}$, $T^{\alpha\beta}$…

General Relativity and Quantum Cosmology · Physics 2022-04-12 Z. Yousaf , M. Z. Bhatti , S. Khan , P. K. Sahoo

This paper explores hydrodynamics and hydrostatic of a star in post-Newtonian approximation of massive Bran-Dicke gravity. We study approximated solution of the field equations upto $O(c^{-4})$ and generalize Euler equation of motion. We…

General Relativity and Quantum Cosmology · Physics 2016-05-11 M. Sharif , Rubab Manzoor

We show that magnetic fields stronger than about $10^{15}$ G are able to suppress the development of the hydrodynamical bar-mode instability in relativistic stars. The suppression is due to a change in the rest-mass density and angular…

General Relativity and Quantum Cosmology · Physics 2015-06-17 Luca Franci , Roberto De Pietri , Kyriaki Dionysopoulou , Luciano Rezzolla

We use a modified Einstein-Maxwell gravity to study stability of an electrostatic spherical star. Correction terms in this model are scalers which are made from contraction of Ricci tensor and electromagnetic vector potential. Our…

General Relativity and Quantum Cosmology · Physics 2023-12-05 Hossein Ghaffarnejad , Tohid Ghorbani , Firoozeh Eidizadeh

In the present work, we have searched the existence of anisotropic and non-singular compact star in the $f(R,T)$ gravity by taking into account the non-exotic equation of state (EoS). In order to obtain the solutions of the matter content…

General Relativity and Quantum Cosmology · Physics 2020-07-02 Anil Kumar Yadav , Monimala Mondal , Farook Rahaman

We consider perfect fluid bodies (stars) in general relativity, characterized by particle number density and entropy per particle. A star is said to be in dynamic equilibrium if it is a stationary, axisymmetric solution to the…

General Relativity and Quantum Cosmology · Physics 2014-01-22 Stephen R. Green , Joshua S. Schiffrin , Robert M. Wald

The equilibrium configuration of white dwarfs composed of a charged perfect fluid are investigated in the context of the $f(R,\mathcal{T})$ gravity, for which $R$ and $\mathcal{T}$ stand for the Ricci scalar and the trace of the…

General Physics · Physics 2020-05-13 F. Rocha , G. A. Carvalho , D. Deb , M. Malheiro