Gravitomagnetic tidal resonance in neutron-star binary inspirals. (arXiv:2003.10427v2 [gr-qc] UPDATED)
<a href="http://arxiv.org/find/gr-qc/1/au:+Poisson_E/0/1/0/all/0/1">Eric Poisson</a>
A compact binary system implicating at least one rotating neutron star
undergoes gravitomagnetic tidal resonances as it inspirals toward its final
merger. These have a dynamical impact on the phasing of the emitted
gravitational waves. The resonances are produced by the inertial modes of
vibration of the rotating star. Four distinct modes are involved, and the
resonances occur within the frequency band of interferometric
gravitational-wave detectors when the star spins at a frequency that lies
within this band. The resonances are driven by the gravitomagnetic tidal field
created by the companion star; this is described by a post-Newtonian vector
potential, which is produced by the mass currents associated with the orbital
motion. These resonances were identified previously by Flanagan and Racine
[Phys. Rev. D 75, 044001 (2007)], but these authors accounted only for the
response of a single mode, the r-mode, a special case of inertial modes. All
four relevant modes are included in the analysis presented in this paper. The
total accumulated gravitational-wave phase shift is shown to range from
approximately $10^{-2}$ radians when the spin and orbital angular momenta are
aligned, to approximately $10^{-1}$ radians when they are anti-aligned. Such
phase shifts will become measurable in the coming decades with the deployment
of the next generation of gravitational-wave detectors (Cosmic Explorer,
Einstein Telescope); they might even come to light within this decade, thanks
to planned improvements in the current detectors. With good constraints on the
binary masses and spins gathered from the inspiral waveform, the phase shifts
deliver information regarding the internal structure of the rotating neutron
star, and therefore on the equation of state of nuclear matter.
A compact binary system implicating at least one rotating neutron star
undergoes gravitomagnetic tidal resonances as it inspirals toward its final
merger. These have a dynamical impact on the phasing of the emitted
gravitational waves. The resonances are produced by the inertial modes of
vibration of the rotating star. Four distinct modes are involved, and the
resonances occur within the frequency band of interferometric
gravitational-wave detectors when the star spins at a frequency that lies
within this band. The resonances are driven by the gravitomagnetic tidal field
created by the companion star; this is described by a post-Newtonian vector
potential, which is produced by the mass currents associated with the orbital
motion. These resonances were identified previously by Flanagan and Racine
[Phys. Rev. D 75, 044001 (2007)], but these authors accounted only for the
response of a single mode, the r-mode, a special case of inertial modes. All
four relevant modes are included in the analysis presented in this paper. The
total accumulated gravitational-wave phase shift is shown to range from
approximately $10^{-2}$ radians when the spin and orbital angular momenta are
aligned, to approximately $10^{-1}$ radians when they are anti-aligned. Such
phase shifts will become measurable in the coming decades with the deployment
of the next generation of gravitational-wave detectors (Cosmic Explorer,
Einstein Telescope); they might even come to light within this decade, thanks
to planned improvements in the current detectors. With good constraints on the
binary masses and spins gathered from the inspiral waveform, the phase shifts
deliver information regarding the internal structure of the rotating neutron
star, and therefore on the equation of state of nuclear matter.
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