Modeling the complete gravitational wave spectrum of neutron star mergers

TL;DR

This paper develops a model linking the main peak frequency of gravitational waves from neutron star mergers to binary tidal interactions, enabling unified descriptions of inspiral and postmerger spectra.

Contribution

It introduces a correlation between the postmerger peak frequency and the tidal coupling constant, independent of many binary parameters, facilitating comprehensive spectral modeling.

Findings

$f_2$ correlates with $^T_2$ across different binary configurations.

The $f_2(^T_2)$ relation is weakly dependent on total mass, mass ratio, and equation of state.

The model enables unified gravitational wave spectrum descriptions.

Abstract

In the context of neutron star mergers, we study the gravitational wave spectrum of the merger remnant using numerical relativity simulations. Postmerger spectra are characterized by a main peak frequency $f_2$ related to the particular structure and dynamics of the remnant hot hypermassive neutron star. We show that $f_2$ is correlated with the tidal coupling constant $\kappa^T_2$ that characterizes the binary tidal interactions during the late-inspiral--merger. The relation $f_2(\kappa^T_2)$ depends very weakly on the binary total mass, mass-ratio, equation of state, and thermal effects. This observation opens up the possibility of developing a model of the gravitational spectrum of every merger unifying the late-inspiral and postmerger descriptions.