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We investigate the behavior of curvature invariants for a large ensemble of neutron stars built with equations of state (EOSs) that satisfy constraints from nuclear theory and perturbative QCD, as well as measurements of neutron-star…

General Relativity and Quantum Cosmology · Physics 2026-04-23 Iván Garibay , Christian Ecker , Luciano Rezzolla

We investigate the reconstruction of standard and generalized Rastall gravity inflationary models, using the scalar spectral index and the Rastall parameter expressed as functions of the number of $e-$folds $N$. Within a general formalism,…

General Relativity and Quantum Cosmology · Physics 2025-12-09 Ramon Herrera , Carlos Rios

In order to examine the rotational effect around neutron star in tensor-vector-scalar (TeVeS) theory, we consider the slowly rotating relativistic stars with a uniform angular velocity. As a result, we find that similar to the case in…

High Energy Astrophysical Phenomena · Physics 2011-01-17 Hajime Sotani

We explore the thermodynamic analysis at the apparent horizon in the framework of Rastall theory of gravity. We take different entropies such as the Bakenstein, logarithmic corrected, power law corrected, and the Renyi entropies. We…

General Physics · Physics 2018-12-04 Kazuharu Bamba , Abdul Jawad , Salman Rafique , Hooman Moradpour

We study magnetospheric structure surrounding rotating magnetized neutron star with nonvanishing NUT (Newman-Tamburino-Unti) parameter. For the simplicity of calculations Goldreich-Julian charge density is analyzed for the aligned neutron…

Astrophysics · Physics 2009-11-13 V. S. Morozova , B. J. Ahmedov , V. G. Kagramanova

Based on a tentative interpretation of gravity as a pressure force, a scalar theory of gravity was previously investigated. It assumes gravitational contraction (dilation) of space (time) standards. In the static case, the same Newton law…

General Physics · Physics 2007-09-05 Mayeul Arminjon

We show that promoting the trace part of the Einstein equations to a trivial identity results in the Newton constant being an integration constant. Thus, in this formulation the Newton constant is a global dynamical degree of freedom which…

General Relativity and Quantum Cosmology · Physics 2021-04-16 Pavel Jiroušek , Keigo Shimada , Alexander Vikman , Masahide Yamaguchi

Rastall's theory is based on the non-conservation of the energy-momentum tensor. We show that, in this theory, if we introduce a two-fluid model, one component representing vacuum energy whereas the other pressureless matter (e.g. baryons…

Cosmology and Nongalactic Astrophysics · Physics 2012-04-27 Carlos E. M. Batista , Mahamadou H. Daouda , Júlio C. Fabris , Oliver F. Piattella , Davi C. Rodrigues

Non-perturbative studies of quantum gravity have recently suggested the possibility that the strength of gravitational interactions might slowly increase with distance. Here a set of generally covariant effective field equations are…

High Energy Physics - Theory · Physics 2011-07-19 Herbert W. Hamber , Ruth M. Williams

In this work we investigate neutron stars (NS) in $f(\mathcal{R,T})$ gravity for the case $R+2\lambda\mathcal{T}$, $\mathcal{R}$ is the Ricci scalar and $\mathcal{T}$ the trace of the energy-momentum tensor. The hydrostatic equilibrium…

High Energy Astrophysical Phenomena · Physics 2021-01-01 R. Lobato , O. Lourenço , P. H. R. S. Moraes , C. H. Lenzi , M. de Avellar , W. de Paula , M. Dutra , M. Malheiro

I propose an alternative $f(R)$ theory of gravity constructed by applying the function $f$ directly to the Ricci tensor instead of the Ricci scalar. The main goal of this study is to derive the resulting modified Einstein equations for the…

General Relativity and Quantum Cosmology · Physics 2017-08-16 Tomasz Stachowiak

Static spherically-symmetric matter distributions whose energy-momentum tensor is characterized by a non-negative trace are studied analytically within the framework of general relativity. We prove that such field configurations are…

General Relativity and Quantum Cosmology · Physics 2015-06-23 Shahar Hod

We consider the sector of Horndeski's gravity characterized by the coupling between the kinetic scalar field term and the Einstein tensor. We numerically construct neutron star configurations where the external geometry is identical to the…

General Relativity and Quantum Cosmology · Physics 2015-09-02 Adolfo Cisterna , Térence Delsate , Massimiliano Rinaldi

The stability properties of the Einstein Static solution of General Relativity are altered when corrective terms arising from modification of the underlying gravitational theory appear in the cosmological equations. In this paper the…

General Relativity and Quantum Cosmology · Physics 2014-11-21 Rosangela Canonico , Luca Parisi

Following the general formalism presented by Rezzolla, Ahmedov and Miller (MNRAS, 322, 723 2001), we here derive analytic solutions of the electromagnetic fields equations in the internal and external background spacetime of a slowly…

General Relativity and Quantum Cosmology · Physics 2007-05-23 L. Rezzolla , B. J. Ahmedov , J. C. Miller

Neutron stars are known to host extremely powerful magnetic fields. Among other effects, one of the consequences of harbouring such fields is the deformation of the neutron star structure, leading, together with rotation, to the emission of…

High Energy Astrophysical Phenomena · Physics 2021-10-27 J. Soldateschi , N. Bucciantini , L. Del Zanna

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 analyse the vacuum static spherically symmetric space-time for a specific class of non-conservative theories of gravity based on the Rastall's theory. We obtain a new vacuum solution which has the same structure as the Schwarzschild-de…

General Relativity and Quantum Cosmology · Physics 2016-06-15 A. M. Oliveira , H. E. S. Velten , J. C. Fabris

The merger remnant of a binary neutron star coalescence is initially strongly differentially rotating. Some properties of these remnants can be accurately modeled through building equilibrium neutron star models. In the present paper, we…

General Relativity and Quantum Cosmology · Physics 2023-08-02 Kalin V. Staykov , Daniela D. Doneva , Lavinia Heisenberg , Nikolaos Stergioulas , Stoytcho S. Yazadjiev

In experimental proposals published in the last two decades, a so called frozen spin storage ring concept was proposed for setting upper experimental bounds to electric dipole moment (EDM) of elementary particles. In a recent paper of ours,…

General Relativity and Quantum Cosmology · Physics 2019-09-18 Andras Laszlo