Nuclear Physics with Gravitational Waves from Neutron Stars Disrupted by Black Holes

Abstract

Gravitational waves from neutron star–black hole (NSBH) mergers that undergo tidal disruption provide a potential avenue to study the equation of state of neutron stars and hence the behavior of matter at its most extreme densities. We present a phenomenological model for the gravitational-wave signature of tidal disruption, which allows us to measure the disruption time. We carry out a study with mock data, assuming an optimistically nearby NSBH event with parameters tuned for measuring the tidal disruption. We show that a two-detector network of 40 km Cosmic Explorer instruments can measure the time of disruption with a precision of ≈0.5 ms, which corresponds to a constraint on the neutron star radius of ≈0.7 km (90% credibility). This radius constraint is wider than the constraint obtained by measuring the tidal deformability of the neutron star of the same system during the inspiral. Moreover, the neutron star radius is likely to be more tightly constrained using binary neutron star mergers. While NSBH mergers are important for the information they provide about stellar and binary astrophysics, they are unlikely to provide insights into nuclear physics beyond what we will already know from binary neutron star mergers.

Observation of Gravitational Waves from the Coalescence of a 2.5–4.5 M ⊙ Compact Object and a Neutron Star

“…compactness of the neutron star (Pannarale et al 2011;Foucart 2012;Foucart et al 2018;Krüger & Foucart 2020). While the disruption probability of the neutron star in GW230529 can be inferred based on the binary parameters, we are unlikely to directly observe the disruption in the GW signal without next-generation observatories (Clarke et al 2023).…”

A Channel to Form Fast-spinning Black Hole–Neutron Star Binary Mergers as Multimessenger Sources. II. Accretion-induced Spin-up

“…Tidal disruption, however, is only expected for a fraction of the BHNS population under certain system parameters. More specifically, the systems that have a low-mass NS component with a stiff equation of state (EoS) and a low-mass BH with a high projected aligned spin can more easily generate tidal disruption and generate bright EM signals 10 (e.g., Shibata et al 2009;Kyutoku et al 2015;Foucart et al 2018;Barbieri et al 2019;Zhu et al 2021aZhu et al , 2021bRaaijmakers et al 2021;Zhu et al 2022b;Clarke et al 2023;Sarin et al 2023). Among the above parameters, the BH-aligned spin could be one of the most critical parameters that affect the tidal disruption and EM detection for the population of a BHNS merger in the Universe.…”