Nonradial oscillations of slowly and differentially rotating compact stars

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

doi:10.1103/physrevd.75.064019

Cited by 27 publications

(38 citation statements)

References 49 publications

(82 reference statements)

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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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Section: Discussionmentioning

confidence: 99%

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

2014

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“…We have chosen the so called B-models [18,19], which represent differentially rotating polytropic stars with central rest mass density ρ c = 7.91 × 10 14 g cm −3 and polytropic parameters Γ = 2 and K = 217.86 km Table I.…”

Section: A Stellar Modelsmentioning

confidence: 99%

“…Still the non-axisymmetric perturbations of differentially rotating relativistic stars have not been treated by any method yet, this paper is the first attempt to address the problem. Actually, in an earlier paper we derived, in the perturbative framework of general relativity, the equations describing the oscillations of a slowly and differentially rotating neutron star in the Cowling approximation [19] (from now on Paper I). Here we study the effect of differential rotation on the oscillation spectrum.…”

Section: Introductionmentioning

confidence: 99%

Nonaxisymmetric oscillations of differentially rotating relativistic stars

2008

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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 relativistic j-constant rotation law. The oscillation spectrum is studied versus three main parameters: the stellar compactness M/R, the degree of differential rotation A and the number of maximun couplings ℓmax. It is shown that the rotational splitting of the non-axisymmetric modes is strongly enhached by increasing the compactness of the star and the degree of differential rotation. Finally, we investigate the relation between the fundamental quadrupole mode and the corotation band of differentially rotating stars.

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“…The effect of differential rotation on the frequencies of stellar modes of oscillation in the Cowling approximation was already investigated in a more preliminary way in [15,16] (f and p modes) and [17] (f and r-modes).…”

Section: Introductionmentioning

confidence: 99%

R -mode frequencies of rapidly and differentially rotating relativistic neutron stars

Jasiulek

Chirenti

2017

Phys. Rev. D

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R-modes of neutron stars could be a source of gravitational waves for ground based detectors. If the precise frequency σ is known, guided gravitational wave searches with enhanced detectability are possible. Because of its physical importance many authors have calculated the r-mode frequency. For the dominant mode, the associated gravitational wave frequency is 4/3 times the angular velocity of the star Ω, subject to various corrections of which relativistic and rotational corrections are the most important. This has led several authors to investigate the dependence of the r-mode frequency on factors such as the relativistic compactness parameter (M/R) and the angular velocity of stars with different equations of state. The results found so far, however, are almost independent of the equation of state. Here we investigate the effect of rapid rotation and differential rotation on σ. We evolve the perturbation equations using the Cowling approximation by applying finite differencing methods to compute the r-mode frequency for a series of rotating neutron stars with polytropic equations of state. We find that rotational effects in the r-mode frequency can be larger than relativistic effects for rapidly spinning stars with low compactness, reducing the observed frequency. Differential rotation also acts to decrease σ, but its effect inscreases with the compactness. The results presented here are relevant to the design of gravitational wave and electromagnetic r-mode searches.

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Nonradial oscillations of slowly and differentially rotating compact stars

Cited by 27 publications

References 49 publications

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

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

Nonaxisymmetric oscillations of differentially rotating relativistic stars

R -mode frequencies of rapidly and differentially rotating relativistic neutron stars

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