Relativistic g-modes in rapidly rotating neutron stars

Gaertig, Erich; Kokkotas, Kostas D.

doi:10.1103/physrevd.80.064026

Cited by 53 publications

(56 citation statements)

References 40 publications

(71 reference statements)

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“…The asymptotic behavior of the homogeneous solution is given by setting α = 0 in Eq. (92), which is the same as Eq. (90) withω c being replaced by w c .…”

Section: Solution To O(χ )mentioning

confidence: 57%

“…(80) and (84), while the asymptotic behavior of the solution that is regular at the NS center is given in Eq. (92). The asymptotic behavior of the homogeneous solution is given by setting α = 0 in Eq.…”

Section: Solution To O(χ )mentioning

confidence: 99%

“…As in GR [88,89] and in TeVeS [90], the spectrum for toroidal oscillations of slowly-rotating stars should also be continuous in dynamical CS gravity. However, this might be an artifact of the slow-rotation limit, since in GR, the spectrum becomes discrete for fast-rotating NSs [91,92]. In principle, if the maximum and/or the minimum of the toroidal oscillation frequencies and the moment of inertia are independently determined, one can break the degeneracy between the gravitational theory and the EoS, and hence test GR [90].…”

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Isolated and binary neutron stars in dynamical Chern-Simons gravity

et al. 2013

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In Ref.[1], the Chern-Simons correction to the osculating orbital elements due to the dipole-dipole interaction for the scalar field was derived in Eq. (130) by integrating out the interaction Lagrangian, which was taken to be the kinetic term for the scalar field [Eq. (122) in [1]], using the scalar field solution. However, such kinetic term only leads to the left-hand side of the evolution equation for the scalar field, i.e.where J is the effective source term of the scalar field equation [2]. In order to obtain the correct interaction Lagrangian, one also needs to include the source term (L source ) that reproduces the right-hand side of the above evolution equation. The Lagrangian density for such an additional term is given by −ϑJ. Therefore, Eq. (126) needs to be changed towhere L source,int is the interaction part of the source term Lagrangian density. Notice that, by accounting for such additional term, the sign of the interaction Lagrangian now flips. This means that the sign in Eqs. (127), (129) and (130) needs to be reversed. The results in Sec. IX B are unaffected since we have neglected contribution from the dipole-dipole interaction because the spin of the secondary pulsar in the double binary pulsar is much smaller than that of the primary. We also report errors in App. B of [1]. In this appendix, we calculated dissipative corrections to the energy and angular momentum energy flux emitted from neutron star binaries based on calculations in [2]. However, some terms in the perturbed scalar and metric field equations were not properly accounted for in [2]. Taking these terms into account, we found that corrections to the gravitational energy and angular momentum flux due to metric perturbations enter at third post-Newtonian order relative to general relativity, which is of 1 post-Newtonian order higher than the effect due to the scalar field. Therefore, Apps. B.1.b and B.2.b in [1] are now irrelevant. We discuss this in more detail in [3].On the other hand, the scalar energy flux in App. B.1.a is affected as follows. First, the far-zone solution for the scalar field in Eq. (B3) becomesThen, the scalar energy flux in Eqs. (B5) and (B6) becomesrespectively. Finally, Eq. (B8) is corrected to T. Tanaka, Phys. Rev., D85, 064022 (2012), arXiv:1110.5950 [gr-qc].[3] K. Yagi, L. C. Stein, N. Yunes, and T. Tanaka, Phys. Rev., D93, 029902 (2016D93, 029902 ( ), arXiv:1110. We study isolated and binary neutron stars in dynamical Chern-Simons gravity. This theory modifies the Einstein-Hilbert action through the introduction of a dynamical scalar field coupled to the Pontryagin density. We here treat this theory as an effective model, working to leading order in the Chern-Simons coupling. We first construct isolated neutron star solutions in the slow-rotation expansion to quadratic order in spin. We find that isolated neutron stars acquire a scalar dipole charge that corrects its spin angular momentum to linear order in spin and corrects its mass and quadrupole moment to quadratic order in spin, as measured by ...

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“…The asymptotic behavior of the homogeneous solution is given by setting α = 0 in Eq. (92), which is the same as Eq. (90) withω c being replaced by w c .…”

Section: Solution To O(χ )mentioning

confidence: 57%

Section: Solution To O(χ )mentioning

confidence: 99%

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confidence: 99%

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Isolated and binary neutron stars in dynamical Chern-Simons gravity

et al. 2013

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“…Also another version of the iterated CN method was proposed in [5] and it was found that the last algorithm has better properties even providing only the first order of accuracy. Different versions of the iterated CN method were used in numerical relativity by a number of authors (e.g., [3,4,[6][7][8] and references therein).…”

Section: Introductionmentioning

confidence: 99%

On iterated Crank–Nicolson methods for hyperbolic and parabolic equations

Bourchtein

2010

Computer Physics Communications

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“…Only the non-axisymmetric modes, though, are prone to CFS instability. Because of the complexity of the problem, most of the studies in this case were performed in the linear regime employing the Cowling approximation [3,4,27,29,30,32], where the spacetime degrees of freedom are neglected and only the fluid variables are evolved in time. The only exceptions are the studies in the conformal flatness approximation [26,31] where a few exemplary sequences with polytropic equation of state where examined, and the full general relativistic nonlinear results in [28].…”

Section: Introductionmentioning

confidence: 99%

Oscillation modes of rapidly rotating neutron stars in scalar-tensor theories of gravity

2017

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We perform the first study of the oscillation frequencies of rapidly rotating neutron stars in alternative theories of gravity, focusing mainly on the fundamental f -modes. We concentrated on a particular class of alternative theories -the (massive) scalar-tensor theories. The generalization to rapid rotation is important because on one hand the rapid rotation can magnify the deviations from general relativity compared to the static case and on the other hand some of the most efficient emitters of gravitational radiation, such as the binary neutron star merger remnants, are supposed to be rotating close to their Kepler (mass-shedding) limits shortly after their formation. We have constructed several sequences of models starting from the nonrotating case and reaching up to the Kepler limit, with different values of the scalar-tensor theory coupling constant and the scalar field mass. The results show that the deviations from pure Einstein's theory can be significant especially in the case of nonzero scalar field mass. An important property of the oscillation modes of rapidly rotating stars is that they can become secularly unstable due to the emission of gravitational radiation, that is so-called Chandrasekhar-Friedman-Schutz instability. Such unstable modes are efficient emitters of gravitational radiation. Our studies show that the inclusion of nonzero scalar field would decrease the threshold value of the normalized angular momentum where this instability stars to operate, but the growth time of the instability seems to be increased compared to pure general relativity.

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Relativistic g-modes in rapidly rotating neutron stars

Cited by 53 publications

References 40 publications

Isolated and binary neutron stars in dynamical Chern-Simons gravity

Isolated and binary neutron stars in dynamical Chern-Simons gravity

On iterated Crank–Nicolson methods for hyperbolic and parabolic equations

Oscillation modes of rapidly rotating neutron stars in scalar-tensor theories of gravity

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