Nonlinear mode-tide coupling in coalescing binary neutron stars with relativistic corrections
Nonlinear mode-tide coupling in coalescing binary neutron stars with relativistic corrections
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DOI：
10.1103/physrevd.106.083001
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发表时间：
2021-07
影响因子：
5
通讯作者：
Fatemeh Hossein Nouri;S. Bose;Matthew D. Duez;A. Das
中科院分区：
文献类型：
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作者：
Fatemeh Hossein Nouri;S. Bose;Matthew D. Duez;A. Das
在广义相对论中计算了非自旋中子星星的内模及其潮汐度规扰动，并确定了相对论修正对模耦合的影响。有人声称，在中子星星双星系统中，一颗中子星星可能会发生一种新的流体动力学不稳定性，这种不稳定性是由伴星的潮汐场与其中成对的p模和g模的非线性耦合触发的，因为双星系统正朝着合并的方向旋转。这种“PG“不稳定性可能是重要的，因为它可以通过提取轨道能量来影响双星的内旋相位，从而可能导致它们的引力波形与理论模型预测的引力波形有很大的偏差，这可能导致不正确的参数估计，最好的情况下，或者合并未被发现，最坏的情况下，由于使用缺陷的波形模型。另一方面，更好地模拟这种不稳定性及其对双星轨道的影响可以揭示一种新的现象，并通过引力波观测揭示恒星不稳定性。到目前为止，所有的模-潮耦合不稳定性研究都是在牛顿微扰理论中进行的。中子星是紧凑的物体，因此相对论修正可能很重要。我们提出并测试了一个新的代码来计算非旋转相对论恒星的相对论本征模。我们使用这些相对论潮汐和中子星星本征模计算模式潮汐耦合强度（MTCS）的几个选定的状态方程。因此计算的MTCS可以是最多百分之几十的不同，从它的纯牛顿值，但我们确认的依赖性轨道分离和状态方程的牛顿计算发现。对于某些物态方程，MTCS对中子星星壳区域非常敏感，这表明了准确处理这一区域的重要性。
We compute the internal modes of a nonspinning neutron star and its tidal metric perturbation in general relativity, and determine the effect of relativistic corrections to the modes on mode coupling. Claims have been made that a new hydrodynamic instability can occur in a neutron star in a binary neutron star system triggered by the nonlinear coupling of the companion's tidal field to pairs of p-modes and g-modes in it as the binary inspirals toward merger. This"PG"instability may be significant since it can influence the binary's inspiral phase by extracting orbital energy, thereby potentially causing large deviations in their gravitational waveforms from those predicted by theoretical models that do not account for it. This can result in incorrect parameter estimation, at best, or mergers going undetected, at worst, owing to the use of deficient waveform models. On the other hand, better modeling of this instability and its effect on binary orbits can unravel a new phenomenon and shed light on stellar instabilities, via gravitational wave observations. So far, all mode-tide coupling instability studies have been formulated in Newtonian perturbation theory. Neutron stars are compact objects, so relativistic corrections might be important. We present and test a new code to calculate the relativistic eigenmodes of nonrotating relativistic stars. We use these relativistic tide and neutron star eigenmodes to compute the mode-tide coupling strength (MTCS) for a few selected equations of state. The MTCS thus calculated can be at most tens of percent different from its purely Newtonian value, but we confirm the dependencies on orbital separation and equation of state found by Newtonian calculations. For some equations of state, the MTCS is very sensitive to the neutron star crust region, demonstrating the importance of treating this region accurately.