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The present paper is devoted to a study of the equilibrium configurations of slowly rotating anisotropic stars in the framework of general relativity. For that purpose, we provide the equations of structure where the rotation is treated to…

General Relativity and Quantum Cosmology · Physics 2024-07-23 Philip Beltracchi , Camilo Posada

We obtain a class of anisotropic spherically symmetric relativistic solutions of compact objects in hydrostatic equilibrium in the $f(R,T) =R+2\chi T$ modified gravity, where $R$ is the Ricci scalar, $T$ is the trace of the energy momentum…

General Physics · Physics 2020-09-18 S. Dey , A. Chanda , B. C. Paul

We propose a new method to study the quasi-normal modes of rotating relativistic stars. Oscillations are treated as perturbations in the frequency domain of the stationary, axisymmetric background describing a rotating star. The perturbed…

General Relativity and Quantum Cosmology · Physics 2008-11-26 V. Ferrari , L. Gualtieri , S. Marassi

In this paper, the gravitational field equations for static spherically symmetric perfect fluid models with a polytropic equation of state, $p=k\rho^{1+1/n}$, are recast into two complementary 3-dimensional {\it regular} systems of ordinary…

General Relativity and Quantum Cosmology · Physics 2009-10-31 U. S. Nilsson , C. Uggla

We report on numerical results from an independent formalism to describe the quasi-equilibrium structure of nonsynchronous binary neutron stars in general relativity. This is an important independent test of controversial numerical…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Pedro Marronetti , Grant J. Mathews , James R. Wilson

By using the Cowling approximation, quasi-radial modes of rotating general relativistic stars are computed along equilibrium sequences from non-rotating to maximally rotating models. The eigenfrequencies of these modes are decreasing…

Astrophysics · Physics 2008-11-26 S'i. Yoshida , Y. Eriguchi

The current theoretical development identified as the gravitational decoupling via Complete Geometric Deformation (CGD) method that has been introduced to explore the nonmetricity $Q$ effects in relativistic astrophysics. In the present…

General Relativity and Quantum Cosmology · Physics 2023-02-06 S. K. Maurya , Ksh. Newton Singh , Santosh V Lohakare , B. Mishra

When a relativistic star rotates slowly and rigidly, centrifugal forces flatten it slightly, thereby catalyzing a small admixture of quadrupolar vibration into its radial modes and a damping of the resulting quasi-radial modes. The damping…

General Relativity and Quantum Cosmology · Physics 2025-09-09 James B. Hartle , Kip S. Thorne

Non-rotating neutron stars are generally treated in theoretical studies as perfect spheres. Such a treatment, however, may not be correct if strong magnetic fields are present (such as for magnetars) and/or the pressure of the matter in the…

Solar and Stellar Astrophysics · Physics 2015-04-14 O. Zubairi , W. Spinella , A. Romero , R. Mellinger , F. Weber , M. Orsaria , G. Contrera

We carry out 3-D numerical simulations of the dynamical instability in rapidly rotating stars initially modeled as polytropes with n = 1.5, 1.0, and 0.5. The calculations are done with a SPH code using Newtonian gravity, and the…

General Relativity and Quantum Cosmology · Physics 2010-11-19 Janet L. Houser , Joan M. Centrella

We investigate the evolution of rigidly and differentially rotating protoneutron stars (PNSs) during the first twenty seconds of their life. We solve the equations describing stationary axisymmetric configurations in general relativity…

Astrophysics · Physics 2007-05-23 Loic Villain , Jose A. Pons , Pablo Cerda-Duran , Eric Gourgoulhon

A new numerical code for computing stationary axisymmetric rapidly rotating stars in general relativity is presented. The formulation is based on a fully constrained-evolution scheme for 3+1 numerical relativity using the Dirac gauge and…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Lap-Ming Lin , Jerome Novak

We introduce our approaches, in particular the modifications of the primitive recovery procedure, to handle bare quark stars in numerical relativity simulations. Reliability and convergence of our implementation are demonstrated by evolving…

General Relativity and Quantum Cosmology · Physics 2021-06-09 Enping Zhou , Kenta Kiuchi , Masaru Shibata , Antonios Tsokaros , Koji Uryu

Equilibrium models of differentially rotating nascent neutron stars are constructed, which represent the result of the accretion induced collapse of rapidly rotating white dwarfs. The models are built in a two-step procedure: (1) a rapidly…

Astrophysics · Physics 2008-11-26 Yuk Tung Liu , Lee Lindblom

We present new results on dynamical instabilities in rapidly rotating neutron-stars. In particular, using numerical simulations in full General Relativity, we analyse the effects that the stellar compactness has on the threshold for the…

Astrophysics · Physics 2008-11-26 G. M. Manca , L. Baiotti , R. De Pietri , L. Rezzolla

Determining the differential-rotation law of compact stellar objects produced in binary neutron stars mergers or core-collapse supernovae is an old problem in relativistic astrophysics. Addressing this problem is important because it…

General Relativity and Quantum Cosmology · Physics 2017-08-16 Matthias Hanauske , Kentaro Takami , Luke Bovard , Luciano Rezzolla , José A. Font , Filippo Galeazzi , Horst Stöcker

Quasi-toroidal oscillations in slowly rotating stars are examined in the framework of general relativity. The oscillation frequency to first order of the rotation rate is not a single value even for uniform rotation unlike the Newtonian…

General Relativity and Quantum Cosmology · Physics 2009-10-30 Yasufumi Kojima

We present the extension of our \cocal~- Compact Object CALculator - code to compute general-relativistic initial data for binary compact-star systems. In particular, we construct quasiequilibrium initial data for equal-mass binaries with…

General Relativity and Quantum Cosmology · Physics 2015-06-04 Antonios Tsokaros , Koji Uryu , Luciano Rezzolla

In this work we obtain an anisotropic neutron star solution by gravitational decoupling starting from a perfect fluid configuration which has been used to model the compact object PSR J0348+0432. Additionally, we consider the same solution…

General Relativity and Quantum Cosmology · Physics 2019-10-14 Victor Torres , Ernesto Contreras

We present a numerical scheme that solves the initial value problem in full general relativity for a binary neutron star in quasi-equilibrium. While Newtonian gravity allows for a strict equilibrium, a relativistic binary system emits…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Thomas W. Baumgarte , Stuart L. Shapiro , Gregory B. Cook , Mark A. Scheel , Saul A. Teukolsky