Gravitational waves from the collision of tidally disrupted stars with massive black holes

TL;DR

This study uses advanced simulations to analyze gravitational waves generated by stars colliding with massive black holes, considering various star types and black hole spins, and explores the detectability of these signals.

Contribution

It provides new insights into gravitational wave signals from tidal disruptions, including cases with significant tidal effects and high angular momentum, using comprehensive relativistic hydrodynamics simulations.

Findings

Nonnegligible gravitational waves can be produced despite strong tidal effects.

Gravitational wave signals are detectable even with high black hole spin and star disruption.

Simulations bridge the gap between point-particle models and complete tidal disruption scenarios.

Abstract

We use simulations of hydrodynamics coupled with full general relativity to investigate the gravitational waves produced by a star colliding with a massive black hole when the star's tidal disruption radius lies far outside of the black hole horizon. We consider both main-sequence and white-dwarf compaction stars, and nonspinning black holes, as well as those with near-extremal spin. We study the regime in between where the star can be accurately modeled by a point particle, and where tidal effects completely suppress the gravitational wave signal. We find that nonnegligible gravitational waves can be produced even when the star is strongly affected by tidal forces, as well as when it collides with large angular momentum. We discuss the implications that these results have for the potential observation of gravitational waves from these sources with future detectors.