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We study both analytically and numerically the gravitational fields of stars in f(R) gravity theories. We derive the generalized Tolman-Oppenheimer-Volkov equations for these theories and show that in metric f(R) models the Parameterized…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Kimmo Kainulainen , Johanna Piilonen , Vappu Reijonen , Daniel Sunhede

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 investigate the geodesic structure of realistic static and spherically symmetric spacetimes embedding neutron stars in metric $f(R)$ gravity, focusing on the quadratic Starobinsky model $f(R)=aR^2$ with $a<0$. Neutron-star solutions are…

General Relativity and Quantum Cosmology · Physics 2026-03-10 Néstor Rivero González , Álvaro de la Cruz Dombriz , Gonzalo J. Olmo

In the present work, we obtain the hydrostatic equilibrium configurations of neutron stars in the recently proposed $f(R,\mathcal{L},T)$ theory of gravity, for which $R$ is the Ricci scalar, $\mathcal{L}$ is the matter lagrangian density,…

General Relativity and Quantum Cosmology · Physics 2024-02-26 J. A. S. Fortunato , P. H. R. S. Moraes , E. Brito , J. G. de Lima Júnior , T. S. Guerini

We study the interior spacetimes of stars in the Palatini formalism of f(R) gravity and derive a generalized Tolman-Oppenheimer-Volkoff and mass equation for a static, spherically symmetric star. We show that matching the interior solution…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Kimmo Kainulainen , Vappu Reijonen , Daniel Sunhede

We consider static spherically symmetric stellar configurations in Palatini theories of gravity in which the Lagrangian is an unspecified function of the form $f(R,R_{\mu\nu}R^{\mu\nu})$. We obtain the Tolman-Oppenheimer-Volkov equations…

General Relativity and Quantum Cosmology · Physics 2015-06-12 Gonzalo J. Olmo , Helios Sanchis-Alepuz , Swapnil Tripathi

We consider static spherically symmetric stellar configurations in Palatini theories of gravity in which the Lagrangian is an unspecified function of the form f(R,R_{\mu\nu}R^{\mu\nu}). We obtain the Tolman-Oppenheimer-Volkov equations…

General Relativity and Quantum Cosmology · Physics 2012-11-06 Gonzalo J. Olmo , Helios Sanchis-Alepuz , Swapnil Tripathi

In this work, we systematically derive the Einstein field equations in general relativity and $f(\mathcal{R})$ gravity, the Tolman-Oppenheimer-Volkoff (TOV) equation, and the expressions for axial and polar Tidal Love Numbers (TLNs) for…

General Relativity and Quantum Cosmology · Physics 2023-06-14 Pinaki Roy , Bharat Kumar

We study the structure of neutron stars in f(R) gravity theories with perturbative constraints. We derive the modified Tolman-Oppenheimer-Volkov equations and solve them for a polytropic equation of state. We investigate the resulting…

High Energy Astrophysical Phenomena · Physics 2014-11-20 Alan Cooney , Simon DeDeo , Dimitrios Psaltis

We will briefly discuss the necessary conditions for stability of polytropies in $f(\hat R)$ Palatini gravity and the differences with the General Relativity ones.

General Relativity and Quantum Cosmology · Physics 2020-01-03 Aneta Wojnar

Besides their astrophysical interest, compact stars also provide an arena for understanding the properties of theories of gravity that differ from Einstein's general relativity. Numerous studies have shown that different modified theories…

General Relativity and Quantum Cosmology · Physics 2015-08-05 Kostas Glampedakis , George Pappas , Hector O. Silva , Emanuele Berti

We investigate in this paper the structures of neutron and quark stars in f(T) theory of gravity where T denotes the torsion scalar. Attention is attached to the TOV type equations of this theory and numerical integrations of these…

General Relativity and Quantum Cosmology · Physics 2016-11-29 A. V. Kpadonou , M. J. S. Houndjo , M. E. Rodrigues

The evolution of linear cosmological perturbations in modified theories of gravity is investigated assuming the Palatini formalism. It has been discussed about the stability problem in this model based on the equivalence between f(R)…

General Relativity and Quantum Cosmology · Physics 2008-06-18 Seokcheon Lee

We present interesting aspects of neutron stars (NSs) from the standpoint of a modified theory of gravity called Ho\v{r}ava-Lifshitz (HL) gravity. A deviation from general relativity (GR) in HL gravity can change typical features of the NS…

General Relativity and Quantum Cosmology · Physics 2021-03-03 Kyungmin Kim , John J. Oh , Chan Park , Edwin J. Son

We study static, spherically symmetric equilibrium configurations in extended theories of gravity (ETG) following the notation introduced by Capozziello et {\it al}. We calculate the differential equations for the stellar structure in such…

General Relativity and Quantum Cosmology · Physics 2016-12-22 Aneta Wojnar , Hermano Velten

Although general relativistic cosmological solutions, even in the presence of pressure, can be mimicked by using neo-Newtonian hydrodynamics, it is not clear whether there exists the same Newtonian correspondence for spherical static…

General Relativity and Quantum Cosmology · Physics 2015-06-23 A. M. Oliveira , H. E. S. Velten , J. C. Fabris , I. G. Salako

Heavy-neutrino (or neutralino) stars are studied using the general relativistic equations of hydrostatic equilibrium and the relativistic equation of state for degenerate fermionic matter. The Tolman-Oppenheimer-Volkoff equations are then…

Astrophysics · Physics 2009-10-30 Neven Bilic , Faustin Munyaneza , Raoul D. Viollier

The relativistic equations of hydrostatic equilibrium for a spherically symmetric star, or the Tolman-Oppenheimer-Volkoff equations are known in higher dimensions. In this paper, these equations have been expressed in terms of parameters of…

General Relativity and Quantum Cosmology · Physics 2020-10-21 Manjari Bagchi

Quartic gravity theory is considered with the Einstein-Hilbert Lagrangean $R+aR^{2}+bR_{\mu \nu}R^{\mu \nu},$ $R_{\mu \nu}$ being Ricci\'s tensor and R the curvature scalar. The parameters $a$ and $b$ are taken of order 1 km$^{2}.$…

General Relativity and Quantum Cosmology · Physics 2021-06-16 Emilio Santos

The torsion models have stood out among the proposals for an alternative description of gravity. The simplest of them, the Teleparallel theory, is equivalent to General Relativity and there are many studies that seek to study its extension…

General Relativity and Quantum Cosmology · Physics 2022-12-09 H. G. M. Fortes , J. C. N. de Araujo
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