Impact of a third body on binary neutron star tidal interactions

TL;DR

This paper investigates how a distant third body influences the tidal interactions and dynamics of binary neutron star systems, with implications for gravitational waveform modeling.

Contribution

It introduces a perturbative approach to include third-body effects in binary tidal interaction models, extending previous isolated binary assumptions.

Findings

Third body effects are weak in b-EMRI systems.

Significant impact on b-IMRI systems.

Modified equations for orbital and quadrupole evolution.

Abstract

For waveform modelling of compact binary coalescence, it is conventionally assumed that the binary is in isolation. In this work, we break that assumption and introduce a third body at a distance. The primary goal is to understand how the distant third body would affect the binary dynamics. However, in the present work, we treat the three-body problem perturbatively and study tidal interaction in the binary due to the third body's presence. We introduce appropriate modifications to the equations governing the orbital motions and the evolution equations of the binary component's quadrupole moment. Further, we obtain the radiated energy and accumulated dephasing for the binary. We show that for b-EMRI, the effect is weak in the tidal sector, while for systems such as b-IMRIs, it would be most relevant to study these effects.