Gravitational-wave cutoff frequencies of tidally disruptive neutron star-black hole binary mergers

Understand

Tidal disruption has a dramatic impact on the outcome of neutron star-black hole mergers.

• The phenomenology of these systems can be divided in three classes: nondisruptive, mildly disruptive or disruptive.
• The cutoff frequency of the gravitational radiation produced during the merger (which is potentially measurable by interferometric detectors) is very different in each regime, and when the merger is disuptive it carries information on the neutron star equation of state.
• Here we use semianalytical tools to derive a formula for the critical binary mass ratio $Q=M_{\rm BH}/M_{\rm NS}$ below which mergers are disruptive as a function of the stellar compactness $\mathcal{C}=M_{\rm NS}/R_{\rm NS}$ and the dimensionless black hole spin $\chi$.