Nonaxisymmetric oscillations of differentially rotating relativistic stars

Passamonti, Andrea; Stavridis, Adamantios; Kokkotas, Kostas D.

doi:10.1103/physrevd.77.024029

Cited by 24 publications

(39 citation statements)

References 39 publications

(127 reference statements)

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“…The non‐barotropic evolution code has been tested against two eigenvalue codes developed by Yoshida & Lee (2000) and Passamonti, Stavridis & Kokkotas (2008), respectively. Yoshida & Lee (2000) solve for linear perturbations of slowly rotating neutron stars in Newtonian gravity, whereas Passamonti et al (2008) study the pulsation spectra of slowly rotating relativistic stars in the Cowling approximation. We have compared the first two g‐mode frequencies with the non‐rotating and weakly stratified Newtonian model of Yoshida & Lee (2000), which has Γ β = 2 and Γ f = 2.0004.…”

Section: Resultsmentioning

confidence: 99%

Oscillations of rapidly rotating stratified neutron stars

Passamonti¹,

Haskell²,

Andersson³

et al. 2009

Monthly Notices of the Royal Astronomical Society

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We use time-evolutions of the linear perturbation equations to study the oscillations of rapidly rotating neutrons stars. Our models account for the buoyancy due to composition gradients and we study, for the first time, the nature of the resultant g-modes in a fast spinning star. We provide detailed comparisons of non-stratified and stratified models. This leads to an improved understanding of the relationship between the inertial modes of a non-stratified star and the g-modes of a stratified system. In particular, we demonstrate that each g-mode becomes rotation-dominated, i.e. approaches a particular inertial mode, as the rotation rate of the star is increased. We also discuss issues relating to the gravitational-wave driven instability of the various classes of oscillation modes.Comment: 16 pages, 12 figures, 4 tables, corrected Table

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Section: Resultsmentioning

confidence: 99%

Oscillations of rapidly rotating stratified neutron stars

Passamonti¹,

Haskell²,

Andersson³

et al. 2009

Monthly Notices of the Royal Astronomical Society

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“…One could also study the relations for differentially-rotating NSs in full GR and compare them against Newtonian relations. Such a goal can be achieved by adopting the j-constant rotation law [74] and constructing a differentially-rotating NS solution in full GR [75][76][77].…”

Section: Discussionmentioning

confidence: 99%

Toward realistic and practical no-hair relations for neutron stars in the nonrelativistic limit

2014

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The gravitational properties of astrophysical objects depend sensitively on their internal structure. In Newtonian theory, the gravitational potential of a rotating star can be fully described by an infinite number of multipole moments of its mass distribution. Recently, this infinite number of moments for uniformlyrotating stars were shown semianalytically to be expressible in terms of just the first three: the mass, the spin, and the quadrupole moment of the star. The relations between the various lower multipole moments were additionally shown to depend weakly on the equation of state, when considering neutron stars and assuming single polytropic equations of state. Here we extend this result in two ways. First, we show that the universality also holds for realistic equations of state, thus relaxing the need to use single polytropes. Second, we derive purely analytical universal relations by perturbing the equations of structure about an n ¼ 0 polytrope that reproduce semianalytic results to Oð1%Þ. We also find that the linear-order perturbation vanishes in some cases, which provides further evidence and a deeper understanding of the universality.

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“…temperatures considerably higher than 10 9 K while the matter is in the form of degenerate protons p, neutrons n and electrons e which are not yet superfluid. This will be an extension of this work and the work that has been done for differentially and slowly rotating stars in [38].…”

Section: Discussionmentioning

confidence: 99%

“…larger Γ 1 , there are some larger deviations. Actually, the authors in [1] used a relativistic, time-independent eigenvalue formulation for slowly rotating stars in the Cowling approximation developed and described in [38] and a new Newtonian time-evolution approach for rapidly rotating configurations to show the good agreement between these two independent methods in the case of a nonrotating star. The relative difference between these two schemes never exceeds 7%.…”

Section: Stratified Oscillationsmentioning

confidence: 99%

Relativistic g-modes in rapidly rotating neutron stars

Gaertig

Kokkotas

2009

Phys. Rev. D

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We study the g-modes of fast rotating stratified neutron stars in the general relativistic Cowling approximation, where we neglect metric perturbations and where the background models take into account the buoyant force due to composition gradients. This is the first paper studying this problem in a general relativistic framework. In a recent paper [1], a similar study was performed within the Newtonian framework, where the authors presented results about the onset of CFS-unstable g-modes and the close connection between inertial-and gravity-modes for sufficiently high rotation rates and small composition gradients. This correlation arises from the interplay between the buoyant force which is the restoring force for g-modes and the Coriolis force which is responsible for the existence of inertial modes. In our relativistic treatment of the problem, we find an excellent qualitatively agreement with respect to the Newtonian results.

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Nonaxisymmetric oscillations of differentially rotating relativistic stars

Cited by 24 publications

References 39 publications

Oscillations of rapidly rotating stratified neutron stars

Oscillations of rapidly rotating stratified neutron stars

Toward realistic and practical no-hair relations for neutron stars in the nonrelativistic limit

Relativistic g-modes in rapidly rotating neutron stars

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