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R-modes of neutron stars could be a source of gravitational waves for ground based detectors. If the precise frequency $\sigma$ is known, guided gravitational wave searches with enhanced detectability are possible. Because of its physical…

General Relativity and Quantum Cosmology · Physics 2017-04-05 Michael Jasiulek , Cecilia Chirenti

We investigate the properties of r-mode and inertial mode of slowly rotating, non-isentropic, Newtonian stars, by taking account of the effects of the Coriolis force and the centrifugal force. For the non-isentropic models we consider only…

Astrophysics · Physics 2010-11-19 Shijun Yoshida , Umin Lee

We present an analytic description of the $r$-mode instability in newly-born neutron stars, using the approximation of uniform density. Our computation is consistently accurate to second order in the angular velocity of the star. We obtain…

Astrophysics · Physics 2011-05-23 K. D. Kokkotas , N. Stergioulas

We present first results of the non-linear evolution of rotating relativistic stars obtained with an axisymmetric relativistic hydrodynamics code in a fixed spacetime. As initial data we use stationary axisymmetric and perturbed…

General Relativity and Quantum Cosmology · Physics 2007-05-23 N. Stergioulas , J. A. Font , K. D. Kokkotas

We investigate the properties of $r$-mode oscillations of a slowly rotating neutron star with a solid crust, by taking account of the effects of the Coriolis force. For the modal analysis we employ three-component neutron star models that…

Astrophysics · Physics 2009-10-31 Shijun Yoshida , Umin Lee

An inconsistency between the theoretical analysis and numerical calculations of the relativistic $r$-modes puzzles the neutron star community since the Kojima's finding of the continuous part in the $r$-mode oscillation spectrum in 1997. In…

High Energy Astrophysical Phenomena · Physics 2022-11-16 Kirill Y. Kraav , Mikhail E. Gusakov , Elena M. Kantor

We present a new numerical code to compute non-axisymmetric eigenmodes of rapidly rotating relativistic stars by adopting spatially conformally flat approximation of general relativity. The approximation suppresses the radiative degree of…

General Relativity and Quantum Cosmology · Physics 2013-05-30 Shin'ichirou Yoshida

A numerical method of mode analysis of rapidly rotating relativistic stellar models by the Cowling approximation is applied to rotating neutron stars with realistic equations of state. For selected equations of state, eigenvalues and…

Astrophysics · Physics 2009-10-30 S. Yoshida , Y. Eriguchi

Non-axisymmetric oscillations of differentially rotating stars are studied using both slow rotation and Cowling approximation. The equilibrium stellar models are relativistic polytropes where differential rotation is described by the…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Andrea Passamonti , Adamantios Stavridis , Kostas Kokkotas

The evolution of a neutron-star r-mode driven unstable by gravitational radiation (GR) is studied here using numerical solutions of the full non-linear fluid equations. The amplitude of the mode grows to order unity before strong shocks…

Astrophysics · Physics 2009-10-31 Lee Lindblom , Joel E. Tohline , Michele Vallisneri

We present and discuss the analytical r-mode solution to the linearized hydrodynamic equations of a slowly rotating, Newtonian, barotropic, non-magnetized, perfect-fluid star in which the gravitational radiation reaction force is present.

Astrophysics · Physics 2017-08-23 Óscar J. C. Dias , Paulo M. Sá

We discuss the role of differential rotation in the evolution of the l=2 r-mode instability of a newly born, hot, rapidly-rotating neutron star. It is shown that the amplitude of the r-mode saturates in a natural way at a value that depends…

Astrophysics · Physics 2017-08-23 Paulo M. Sá , Brigitte Tomé

We study the low T/W instability associated with the f-mode of differentially rotating stars. Our stellar models are described by a polytropic equation of state and the rotation profile is given by the standard j-constant law. The…

Solar and Stellar Astrophysics · Physics 2015-06-22 Andrea Passamonti , Nils Andersson

We study nonaxisymmetric perturbations of rotating relativistic stars. modeled as perfect-fluid equilibria. Instability to a mode with angular dependence $\exp(im\phi)$ sets in when the frequency of the mode vanishes. The locations of these…

General Relativity and Quantum Cosmology · Physics 2009-10-30 Nikolaos Stergioulas , John L. Friedman

We develop a new perturbative framework for studying the r-modes of rotating superfluid neutron stars. Our analysis accounts for the centrifugal deformation of the star, and considers the two-fluid dynamics at linear order in the perturbed…

Solar and Stellar Astrophysics · Physics 2015-05-13 B. Haskell , N. Andersson , A. Passamonti

R-modes of a rotating neutron star are unstable because of the emission of gravitational radiation. We explore the saturation amplitudes of these modes determined by nonlinear mode-mode coupling. Modelling the star as incompressible allows…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Jeandrew Brink , Saul A. Teukolsky , Ira Wasserman

Diffferentially rotating stars can support significantly more mass in equilibrium than nonrotating or uniformly rotating stars, according to general relativity. The remnant of a binary neutron star merger may give rise to such a…

Astrophysics · Physics 2009-10-31 Stuart L. Shapiro

We study relativistic star solutions in second-order generalized Proca theories characterized by a $U(1)$-breaking vector field with derivative couplings. In the models with cubic and quartic derivative coupling, the mass and radius of…

General Relativity and Quantum Cosmology · Physics 2018-04-11 Ryotaro Kase , Masato Minamitsuji , Shinji Tsujikawa

We study non-linear axisymmetric pulsations of rotating relativistic stars using a general relativistic hydrodynamics code under the assumption of a conformal flatness. We compare our results to previous simulations where the spacetime…

Astrophysics · Physics 2009-11-11 Harald Dimmelmeier , Nikolaos Stergioulas , Jose A. Font

Axial oscillations relevant to the r-mode instability are studied with slow rotation formalism in general relativity. The approximate equation governing the oscillations is derived with second-order rotational corrections. The equation…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Yasufumi Kojima , Masayasu Hosonuma