A Semi-relativistic Model for Tidal Interactions in BH-NS Coalescing Binaries

TL;DR

This paper introduces a semi-relativistic model to analyze tidal interactions in black hole-neutron star binaries, accounting for relativistic effects on the neutron star's self-gravity, and identifies critical orbital separations relevant for gamma-ray burst scenarios.

Contribution

It presents a novel semi-analytical approach modeling neutron star deformation with relativistic effects in BH-NS binaries, enabling calculation of disruption points.

Findings

Calculated quasi-equilibrium sequences of BH-NS binaries.

Identified critical orbital separations for neutron star disruption.

Implications for short gamma-ray burst formation.

Abstract

We study the tidal effects of a Kerr black hole on a neutron star in black hole-neutron star binary systems using a semi-analytical approach which describes the neutron star as a deformable ellipsoid. Relativistic effects on the neutron star self-gravity are taken into account by employing a scalar potential resulting from relativistic stellar structure equations. We calculate quasi-equilibrium sequences of black hole-neutron star binaries, and the critical orbital separation at which the star is disrupted by the black hole tidal field: the latter quantity is of particular interest because when it is greater than the radius of the innermost stable circular orbit, a short gamma-ray burst scenario may develop.