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Related papers: Anisotropic neutron stars in $R^2$ gravity

200 papers

Both relativistic and non-relativistic two-fluid models of neutron star cores are constructed, using the constrained variational formalism developed by Brandon Carter and co-workers. We consider a mixture of superfluid neutrons and…

Astrophysics · Physics 2008-08-05 N. Chamel

We study the stability of neutron stars with toroidal magnetic fields by magnetohydrodynamic simulation in full general relativity under assumption of axial symmetry. Nonrotating and rigidly rotating neutron stars are prepared for a variety…

Astrophysics · Physics 2008-12-18 Kenta Kiuchi , Masaru Shibata , Shijun Yoshida

A simple classification is given of the anisotropic relativistic star models, resembling the one of charged isotropic solutions. On the ground of this database, and taking into account the conditions for physically realistic star models, a…

General Relativity and Quantum Cosmology · Physics 2018-01-24 B. V. Ivanov

Within the framework of Einstein's General Relativity we study strange quark stars assuming an interacting equation-of-state. Taking into account the presence of anisotropies in a sphere made of ultra dense matter, we employ the formalism…

General Relativity and Quantum Cosmology · Physics 2023-03-09 Angel Rincon , Grigoris Panotopoulos , Ilidio Lopes

We perform fully relativistic calculations of binary neutron stars in corotating, circular orbit. While Newtonian gravity allows for a strict equilibrium, a relativistic binary system emits gravitational radiation, causing the system to…

General Relativity and Quantum Cosmology · Physics 2016-08-25 T. W. Baumgarte , G. B. Cook , M. A. Scheel , S. L. Shapiro , S. A. Teukolsky

The anisotropic influence on the $f$-mode frequency of oscillations and dimensionless tidal deformability of neutron stars is analyzed by employing the nonradial oscillation equations for the complete general relativity frame and tidal…

General Relativity and Quantum Cosmology · Physics 2026-05-27 José D. V. Arbañil , Gabriel O. Cavalheiro , Victor B. T. Alves , Juan M. Z. Pretel , César O. V. Flores , César H. Lenzi

In the present paper we investigate self-consistently slowly rotating neutron and strange stars in R-squared gravity. For this purpose we first derive the equations describing the structure of the slowly rotating compact stars in…

General Relativity and Quantum Cosmology · Physics 2015-06-22 Kalin V. Staykov , Daniela D. Doneva , Stoytcho S. Yazadjiev , Kostas D. Kokkotas

We study the main astrophysical properties of differentially rotating neutron stars described as stationary and axisymmetric configurations of a moderately stiff $\Gamma=2$ polytropic fluid. The high level of accuracy and of stability of…

High Energy Astrophysical Phenomena · Physics 2017-03-08 Dorota Gondek-Rosinska , Izabela Kowalska , Loic Villain , Marcus Ansorg , Marcin Kucaba

In general relativity static gaseous atmospheres may be in hydrostatic balance in the absence of a supporting stellar surface, provided that the luminosity is close to the Eddington value. We construct analytic models of optically thin,…

High Energy Astrophysical Phenomena · Physics 2016-01-11 M. Wielgus , W. Kluźniak , A. Sądowski , R. Narayan , M. Abramowicz

In a previous paper, we reported simulations of the evolution of the magnetic field in neutron star cores through ambipolar diffusion, taking the neutrons as a motionless uniform background. However, in real neutron stars, neutrons are free…

High Energy Astrophysical Phenomena · Physics 2020-09-02 F. Castillo , A. Reisenegger , J. A. Valdivia

In this work, we study the impact of anisotropy on slowly rotating neutron stars by extending the Hartle-Thorne formalism in general relativity to include anisotropy in pressure up to second order in the angular velocity. We assess the…

General Relativity and Quantum Cosmology · Physics 2024-10-10 L. M. Becerra , E. A. Becerra-Vergara , F. D. Lora-Clavijo

Neutron star asteroseismology offers a unique opportunity to probe nuclear physics through stellar oscillations. Although the pressure inside of a neutron star is typically assumed to be isotropic, pressure anisotropy can arise from various…

General Relativity and Quantum Cosmology · Physics 2026-01-13 Jihao Yu , Victor Guedes , Shu Yan Lau , Siddarth Ajith , Kent Yagi

The macroscopic model is formulated for a neutron star (NS) as a perfect liquid drop at the equilibrium. We use the leptodermic approximation $a/R\ll 1$, where $a$ is the crust thickness of the effective NS surface (ES), and $R$ is the mean…

Nuclear Theory · Physics 2025-08-07 A. G. Magner , S. P. Maydanyuk , A. Bonasera , H. Zheng , T. Depastas , A. I. Levon , U. V. Grygoriev

This thesis investigates compact astrophysical objects within modified theories of gravity, focusing on neutron stars and strange stars. The work studies their internal structure, equilibrium, and stability in gravitational frameworks based…

General Relativity and Quantum Cosmology · Physics 2026-05-26 Sneha Pradhan

Concerning the stability of two-fluid star models, we prove the rigorous equivalence of two independent determining methods for mixed stars, after a brief review of the hybrid star case. Our derivations apply to general multi-fluid cases,…

High Energy Astrophysical Phenomena · Physics 2025-12-02 Xiao-Ding Zhou , Tian-Shun Chen , Si-Man Wu , Kilar Zhang

Neutron Stars are natural laboratories where fundamental properties of matter under extreme conditions can be explored. Modern nuclear physics input as well as many-body theories are valuable tools which may allow us to improve our…

Solar and Stellar Astrophysics · Physics 2015-06-11 V. de la Mota , F. Sébille , Ph. Eudes

The understanding of stellar structure represents the crossroads of our theories of the nuclear force and the gravitational interaction under the most extreme conditions observably accessible. It provides a powerful probe of the strong…

General Relativity and Quantum Cosmology · Physics 2020-09-15 Gonzalo J. Olmo , Diego Rubiera-Garcia , Aneta Wojnar

We present the first numerical relativity simulations of the gravitational scattering of two neutron stars. Constraint-satisfying initial data for two equal-mass nonspinning sequences are constructed at fixed energy and various initial…

General Relativity and Quantum Cosmology · Physics 2025-12-03 Joan Fontbuté , Sebastiano Bernuzzi , Piero Rettegno , Simone Albanesi , Wolfgang Tichy

We analyse the gravitational behaviour of a relativistic heat conducting fluid in a shear-free spherically symmetric spacetime. We show that the isotropy of pressure is a consistency condition which realises a second order nonlinear…

General Relativity and Quantum Cosmology · Physics 2015-12-31 B. P. Brassel , S. D. Maharaj , G. Govender

We investigate the equilibrium and radial stability of spherically symmetric relativistic stars, considering a polytropic equation of state (EoS), within the framework of $f(R,T)$ gravity with a conservative energy-momentum tensor. Both…

General Relativity and Quantum Cosmology · Physics 2021-08-26 Juan M. Z. Pretel , Sergio E. Jorás , Ribamar R. R. Reis , José D. V. Arbañil