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This paper is the first in a sequence of three devoted to the formulation of a theory of self-gravitating anisotropic fluids in both Newtonian and relativistic gravity. In this first paper we set the stage, place our work in the context of…

General Relativity and Quantum Cosmology · Physics 2024-06-06 Tom Cadogan , Eric Poisson

Using an energy variational method, we calculate quasi-equilibrium configurations of binary neutron stars modeled as compressible triaxial ellipsoids obeying a polytropic equation of state. Our energy functional includes terms both for the…

Astrophysics · Physics 2009-10-30 James C. Lombardi , Frederic A. Rasio , Stuart L. Shapiro

We study the gravitational collapse of a spherically symmetric anisotropic relativistic star within Einstein theory of gravity making use of one of our recently developed collapsing stellar models [{\it Astrophys. Space Sci.} {\bf361} 99…

General Relativity and Quantum Cosmology · Physics 2022-01-05 Shyam Das , Bikash Chandra Paul , Ranjan Sharma

We use oblate axisymmetric dynamical models including dark halos to determine the orbital structure of intermediate mass to massive Coma early-type galaxies. We find a large variety of orbital compositions. Averaged over all sample galaxies…

The Skyrme model is a low energy, effective field theory for QCD which when coupled to a gravitational field provides an ideal semi-classical model to describe neutron stars. We use the Skyrme crystal solution composed of a lattice of…

Solar and Stellar Astrophysics · Physics 2015-06-04 S. G. Nelmes , B. M. A. G. Piette

We model a rotating star as a compressible fluid subject to gravitational forces. In almost all the mathematical literature the entropy is considered to be constant. Here we allow it to be variable. We consider a star that steadily rotates…

Analysis of PDEs · Mathematics 2022-04-19 Juhi Jang , Walter A. Strauss , Yilun Wu

Two distinct non-singular interior models that describe anisotropic spherical configurations are presented in this work. We develop the Einstein field equations and the associated mass function in accordance with a static spherical…

General Relativity and Quantum Cosmology · Physics 2025-10-10 M. Sharif , Tayyab Naseer , Hira Shadab

We investigate the dynamical stability of relativistic, differentially rotating, quasi-toroidal models of neutron stars through hydrodynamical simulations in full general relativity. We find that all quasi-toroidal configurations studied in…

High Energy Astrophysical Phenomena · Physics 2019-08-21 Pedro L. Espino , Vasileios Paschalidis , Thomas W. Baumgarte , Stuart L. Shapiro

In this article, we attempt to find a singularity free solution of Einstein's field equations for compact stellar objects, precisely strange (quark) stars, considering Schwarzschild metric as the exterior spacetime. To this end, we consider…

General Relativity and Quantum Cosmology · Physics 2017-10-19 Debabrata Deb , Sourav Roy Chowdhury , Saibal Ray , Farook Rahaman , B. K. Guha

We investigated Rastall gravity, for an anisotropic star with a static spherical symmetry, whereas the matter-geometry coupling as assumed in Rastall Theory (RT) is expected to play a crucial role in differentiating RT from General…

General Relativity and Quantum Cosmology · Physics 2022-09-07 G. G. L. Nashed , W. El Hanafy

We study the spin-up of the accreting neutron stars with a realistic hyperon-softened equation of state. Using precise 2-D calculations we study the evolutionary tracks of accreting neutron stars in the angular-momentum - frequency plane.…

Astrophysics · Physics 2007-05-23 J. L. Zdunik , P. Haensel , M. Bejger

"Mountains" or non-axisymmetric deformations of rotating neutron stars (NS) efficiently radiate gravitational waves (GW). We consider analogies between NS mountains and surface features of solar system bodies. Both NS and moons such as…

High Energy Astrophysical Phenomena · Physics 2024-10-28 J. A. Morales , C. J. Horowitz

Out-of-equilibrium reactions between different particle species are the main processes contributing to bulk viscosity in neutron stars. In this work, we numerically compare three different approaches to the modeling of bulk viscosity: the…

General Relativity and Quantum Cosmology · Physics 2023-05-23 Giovanni Camelio , Lorenzo Gavassino , Marco Antonelli , Sebastiano Bernuzzi , Brynmor Haskell

Einstein's theory of general relativity predicts that the only stationary configuration of an isolated black hole is the Kerr spacetime, which has a unique multipolar structure and a spherical shape when non-spinning. This is in striking…

General Relativity and Quantum Cosmology · Physics 2020-09-02 Guilherme Raposo , Paolo Pani

This article first reviews the basic physics of rotating stars and their evolution. We examine in particular the changes of the mechanical and thermal equilibrium of rotating stars. An important (predicted and observed) effect is that…

Solar and Stellar Astrophysics · Physics 2011-09-29 Andre Maeder , Georges Meynet

We study low-amplitude crustal oscillations of slowly rotating relativistic stars consisting of a central fluid core and an outer thin solid crust. We estimate the effect of rotation on the torsional toroidal modes and on the interfacial…

General Relativity and Quantum Cosmology · Physics 2009-11-13 M. Vavoulidis , K. D. Kokkotas , A. Stavridis

In our previous treatment of neutron stars, we have developed the model fulfilling global and not local charge neutrality. In order to implement such a model, we have shown the essential role by the Thomas-Fermi equations, duly generalized…

Solar and Stellar Astrophysics · Physics 2014-11-13 R. Belvedere , K. Boshkayev , Jorge A. Rueda , R. Ruffini

Mass loss is a determinant factor which strongly affects the evolution and the fate of massive stars. At low metallicity, stars are supposed to rotate faster than at the solar one. This favors the existence of stars near the critical…

Astrophysics · Physics 2009-11-13 Cyril Georgy , Georges Meynet , André Maeder

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

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
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