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Related papers: Nonradial instabilities in anisotropic neutron sta…

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Here we investigate the axial w quasi-normal modes of neutron stars for several equations of state. In particular, we study the influence of the presence of hyperons in the core of the neutron stars. We have obtained that w-modes can be…

General Relativity and Quantum Cosmology · Physics 2013-07-04 J. L. Blázquez-Salcedo , L. M. González-Romero , F. Navarro-Lérida

In the present work, we study the radial and non-radial perturbative stability of neutron stars in which the matter is disformally coupled to the metric. First, we derive the gravitational and the fluid equations of the neutron star in a…

General Relativity and Quantum Cosmology · Physics 2023-08-08 Hamza Boumaza

We present our study of stability of differentially rotating, axisymmetric neutron stars described by a polytropic equation of state with $\Gamma = 2$. We focus on quasi-toroidal solutions with a degree of differential rotation $\widetilde…

High Energy Astrophysical Phenomena · Physics 2024-02-29 Paweł Szewczyk , Dorota Gondek-Rosińska , Pablo Cerdá-Durán

We investigate nonradial $f$-mode oscillations of protoneutron stars in full general relativity, employing equations of state described by the Brueckner-Hartree-Fock theory or the relativistic mean field model, while assuming isentropy and…

High Energy Astrophysical Phenomena · Physics 2025-12-04 Zi-Yue Zheng , Ting-Ting Sun , Huan Chen , Jin-Biao Wei , Xiao-Ping Zheng , G. F. Burgio , H. -J. Schulze

In this review article, we present the main results from our most recent research concerning the oscillations of fast rotating neutron stars. We derive a set of time evolution equations for the investigation of non-axisymmetric oscillations…

General Relativity and Quantum Cosmology · Physics 2021-10-04 Christian J. Krüger , Kostas D. Kokkotas , Praveen Manoharan , Sebastian H. Völkel

The excitation of the axial quasi-normal modes of a relativistic star by scattered particles is studied by evolving the time dependent perturbation equations. This work is the first step towards the understanding of more complicated…

General Relativity and Quantum Cosmology · Physics 2009-10-31 V. Ferrari , K. D. Kokkotas

We present the results of the first study of global oscillations of relativistic stars with both elastic crusts and interpenetrating superfluid components. For simplicity, we focus on the axial quasi-normal modes. Our results demonstrate…

Solar and Stellar Astrophysics · Physics 2009-07-24 Lars Samuelsson , Nils Andersson

We investigate the properties of anisotropic, spherically symmetric compact stars, especially neutron stars and strange quark stars, made of strongly magnetized matter. The neutron stars are described by SLy equation of state, the strange…

High Energy Astrophysical Phenomena · Physics 2021-12-08 Debabrata Deb , Banibrata Mukhopadhyay , Fridolin Weber

We present an asymptotic theory that describes regular frequency spacings of pressure modes in rapidly rotating stars. We use an asymptotic method based on an approximate solution of the pressure wave equation constructed from a stable…

Solar and Stellar Astrophysics · Physics 2012-09-27 Michael Pasek , François Lignières , Bertrand Georgeot , Daniel R. Reese

We use perturbation theory and the relativistic Cowling approximation to numerically compute characteristic oscillation modes of rapidly rotating relativistic stars which consist of a perfect fluid obeying a polytropic equation of state. We…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Stratos Boutloukos , Hans-Peter Nollert

We study the oscillations modes of differential rotating remnants of binary neutron star inspirals by modeling them as incompressible Riemann ellipsoids parametrized by the ratio $f$ of their internal circulation to the rotation frequency.…

General Relativity and Quantum Cosmology · Physics 2021-12-20 Peter B. Rau , Armen Sedrakian

The spectrum of radial oscillations of neutron stars is systematically studied within two frameworks of viscous relativistic hydrodynamics: the relativistic Navier-Stokes and Israel-Stewart theories. A correspondence is established between…

General Relativity and Quantum Cosmology · Physics 2026-01-09 Raissa F. P. Mendes , Amanda Guerrieri , João V. M. Muniz , Gabriel S. Rocha , Gabriel S. Denicol

We study oscillations and instabilities of relativistic stars using perturbation theory in general relativity and take into account the contribution of a dynamic spacetime. We present the oscillation spectrum as well as the critical values…

General Relativity and Quantum Cosmology · Physics 2020-09-16 C. J. Krüger , K. D. Kokkotas

We consider both mode calculations and time evolutions of axial r-modes for relativistic uniformly rotating non-barotropic neutron stars, using the slow-rotation formalism, in which rotational corrections are considered up to linear order…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Johannes Ruoff , Kostas D. Kokkotas

Neutron stars are highly compact astrophysical objects and therefore of utmost relevance to learn about theories of gravity. Whereas the proper equation of state of the nuclear matter inside neutron stars is not yet known, and a wide range…

General Relativity and Quantum Cosmology · Physics 2022-04-28 Jutta Kunz

In the present paper we examine gravitational wave asteroseismology relations for f-modes of rapidly rotating neutron stars. An approach different to the previous studies is employed - first, the moment of inertia is used instead of the…

Solar and Stellar Astrophysics · Physics 2015-12-09 Daniela D. Doneva , Kostas D. Kokkotas

We investigate how the pulsation frequencies of axial gravitational-wave modes ($w$-modes) in a non-rotating neutron star depend on its composition, particularly when including quarkyonic matter and fermionic dark matter. These modes emerge…

High Energy Astrophysical Phenomena · Physics 2025-09-03 D. Dey , Jeet Amrit Pattnaik , R. N. Panda , S. K. Patra

We investigate axial quasi-normal modes of realistic neutron stars in Einstein-Gauss-Bonnet-dilaton gravity. We consider 8 realistic equations of state containing nuclear, hyperonic, and hybrid matter. We focus on the fundamental curvature…

General Relativity and Quantum Cosmology · Physics 2016-02-03 Jose Luis Blázquez-Salcedo , Luis Manuel González-Romero , Jutta Kunz , Sindy Mojica , Francisco Navarro-Lérida

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

Cold and dense matter may break rotational symmetry spontaneously and thus form an anisotropic phase in the interior of neutron stars. We consider the concrete example of an anisotropic chiral condensate in the form of a chiral density…

Nuclear Theory · Physics 2025-01-22 Orestis Papadopoulos , Andreas Schmitt