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Related papers: Compact Star in General $F(R)$ Gravity: Inevitable…

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This article primarily investigates the existence of the charged compact star under the conformal motion treatment within the context of f(Q) gravity. We have developed two models by implementing the power-law and linear form of conformal…

General Relativity and Quantum Cosmology · Physics 2024-04-02 Sneha Pradhan , P. K. Sahoo

The equation of motion for test particles in $f(R)$ modified theories of gravity is derived. By considering an explicit coupling between an arbitrary function of the scalar curvature, $R$, and the Lagrangian density of matter, it is shown…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Orfeu Bertolami , Christian G. Boehmer , Tiberiu Harko , Francisco S. N. Lobo

In the present work we have investigated a new anisotropic solution for polytropic star in the framework of $4D$ Einstein-Gauss-Bonnet (EGB) gravity. The possibility of determining the masses and radii of compact stars which puts some…

General Relativity and Quantum Cosmology · Physics 2022-09-20 Ksh. Newton Singh , S. K. Maurya , Piyali Bhar , Riju Nag

We consider stability of spherically symmetric solutions in $f(R)$ gravity model proposed by Starobinsky. We find that the model suffers from a severe fine tuning problem when applied to compact objects like neutron stars. The problem can…

General Relativity and Quantum Cosmology · Physics 2010-03-25 I. Thongkool , M. Sami , S. Rai Choudhury

We study the Starobinsky or $R^2$ model of $f(R)=R+\alpha R^2$ for neutron stars with the structure equations represented by the coupled differential equations and the \emph{polytropic} type of the matter equation of state. The junction…

General Relativity and Quantum Cosmology · Physics 2017-10-11 Wei-Xiang Feng , Chao-Qiang Geng , W. F. Kao , Ling-Wei Luo

We investigate a conservative formulation of $f(R,T)$ gravity motivated by a key limitation of several existing approaches: the gravitational function is often reconstructed from a chosen equation of state, making the gravity sector…

General Relativity and Quantum Cosmology · Physics 2026-05-12 Ronaldo V. Lobato , Geanderson A. Carvalho , Carlos E. C. Montaña , Jose F. Rodriguez-Ruiz

We analyse configurations of compact stars in the so-called R-squared gravity in the Palatini formalism. Using a realistic equation of state we show that the mass-radius configurations are lighter than their counterparts in General…

General Relativity and Quantum Cosmology · Physics 2016-12-28 F. A. Teppa Pannia , F. García , S. E. Perez Bergliaffa , M. Orellana , G. E. Romero

We study the dynamical stability against bar-mode deformation of rapidly and differentially rotating stars in the first post-Newtonian approximation of general relativity. We vary the compaction of the star $M/R$ (where $M$ is the…

Astrophysics · Physics 2008-11-26 Motoyuki Saijo , Masaru Shibata , Thomas W. Baumgarte , Stuart L. Shapiro

The present work is focused on the investigation of the existence of compact structures describing anisotropic matter distributions within the framework of modified gravity theories, specifically f(R,$\mathcal{T}$) gravity theory.…

General Relativity and Quantum Cosmology · Physics 2019-08-14 S. K. Maurya , Abdelghani Errehymy , Debabrata Deb , Francisco Tello-Ortiz , Mohammed Daoud

This study explores the behavior of compact stars within the framework of $f(R,L_m,T)$ gravity, focusing on the functional form $f(R,L_m,T) = R + \alpha TL_m$. The modified Tolman-Oppenheimer-Volkoff (TOV) equations are derived and…

General Relativity and Quantum Cosmology · Physics 2024-07-09 Clésio E. Mota , Juan M. Z. Pretel , César O. V. Flores

We reexamine the static and spherical symmetric compact star configuration in the $R^2$ model of the $F(R)$ gravity theory. With asymptotic solutions for the additional scalar degrees of freedom, we refine analysis on the external geometry…

General Relativity and Quantum Cosmology · Physics 2023-05-11 Kota Numajiri , Yong-Xiang Cui , Taishi Katsuragawa , Shin'ichi Nojiri

In this study, we present a generalized spherically symmetric, anisotropic and static compact stellar model in $f(T)$ gravity, where $T$ represents the torsion scalar. By employing the Karmarkar condition we have obtained embedding class 1…

General Relativity and Quantum Cosmology · Physics 2018-11-30 Debabrata Deb , Shounak Ghosh , S. K. Maurya , Maxim Khlopov , Saibal Ray

Modern multi-messenger astronomical observations and heavy ion experiments provide new insights into the structure of compact objects. Nevertheless, much ambiguity remains when it comes to super dense matter above the nuclear saturation…

General Relativity and Quantum Cosmology · Physics 2021-02-03 Victor I. Danchev , Daniela D. Doneva

We investigate a simple generalization of the metric exponential $f(R)$ gravity theory that is cosmologically viable and compatible with solar system tests of gravity. We show that, as compared to other viable $f(R)$ theories, its steep…

Cosmology and Nongalactic Astrophysics · Physics 2013-11-26 M. O'Dwyer , S. E. Joras , I. Waga

The aim of this paper is to study the formation of anisotropic compact stars in modified $f(R)$ theory of gravity, which is the generalization of the Einstein's gravity. To this end, we have used the solution of Krori and Barua to the…

General Physics · Physics 2016-05-04 M. Zubair , G. Abbas

Although $f(R)$ modified gravity models can be made to satisfy solar system and cosmological constraints, it has been shown that they have the serious drawback of the nonexistence of stars with strong gravitational fields. In this paper, we…

Astrophysics · Physics 2009-01-21 Tsutomu Kobayashi , Kei-ichi Maeda

Using a perturbative approach we solve stellar structure equations for low-density (solar-type) stars whose interior is described with a polytropic equation of state in scenarios involving a subset of modified gravity theories. Rather than…

Solar and Stellar Astrophysics · Physics 2019-02-27 M. Cermeño , J. Carro , A. L. Maroto , M. Ángeles Pérez-García

Neutron stars with strong magnetic fields are considered in the framework of f(R) gravity. In order to describe dense matter in magnetic field, the model with baryon octet interacting through $\sigma$$\rho$$\omega$-fields is used. The…

General Relativity and Quantum Cosmology · Physics 2015-06-19 Artyom V. Astashenok , Salvatore Capozziello , Sergei D. Odintsov

We investigate a f(R) modification of gravity that is exponential in the Ricci scalar R to explain cosmic acceleration. The steepness of this dependence provides extra freedom to satisfy solar system and other curvature regime constraints.…

Cosmology and Nongalactic Astrophysics · Physics 2010-01-07 Eric V. Linder

We reconcile seemingly conflicting statements in the literature about the behavior of cosmological solutions in modified theories of gravity where the Einstein-Hilbert Lagrangian for gravity is modified by the addition of a function of the…

Astrophysics · Physics 2008-11-26 Ignacy Sawicki , Wayne Hu