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arXiv · 2110.03494

Relativistic scattering of a fast spinning neutron star by a massive black hole

Kaye Jiale Li·Kinwah Wu·Po Kin Leung·Dinesh Singh
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Abstract

The orbital dynamics of fast spinning neutron stars encountering a massive Black Hole (BH) with unbounded orbits are investigated using the quadratic-in-spin Mathisson-Papapetrou- Dixon (MPD) formulation. We consider the motion of the spinning neutron stars with astrophysically relevant speed in the gravity field of the BH. For such slow-speed scattering, the hyperbolic orbits followed by these neutron stars all have near the e = 1 eccentricity, and have distinct properties compared with those of e >> 1. We have found that compared with geodesic motion, the spin-orbit and spin-spin coupling will lead to a variation of scattering angles at spatial infinity, and this variation is more prominent for slow-speed scattering than fast-speed scattering. Such a variation leads to an observable difference in pulse-arrival-time within a few hours of observation, and up to a few days or months for larger BH masses or longer spinning periods. Such a relativistic pulsar-BH system also emits a burst of gravitational waves (GWs) in the sensitivity band of LISA, and for optimal settings, can be seen up to 100 Mpc away. A radio follow up of such a GW burst with SKA or FAST will allow for measuring the orbital parameters with high accuracy and testing the predictions of General Relativity (GR).

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Kaye Jiale Li, Kinwah Wu, Po Kin Leung, Dinesh Singh. 2021-10-07. Relativistic scattering of a fast spinning neutron star by a massive black hole. https://doi.org/10.1093/mnras%2Fstab2925

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