Prospects for the inference of inertial modes from hypermassive neutron stars with future gravitational-wave detectors

TL;DR

This paper evaluates the potential to detect inertial modes in gravitational waves from long-lived neutron star merger remnants, highlighting the capabilities of future detectors like the Einstein Telescope.

Contribution

It assesses the detectability of inertial modes in post-merger gravitational waves using Bayesian analysis and forecasts detection prospects with current and future detectors.

Findings

Current detectors can detect inertial modes up to 1 Mpc.

Future detectors like the Einstein Telescope could increase detection range by a factor of 10.

Inertial modes provide insights into neutron star properties.

Abstract

Some recent, long-term numerical simulations of binary neutron star mergers have shown that the long-lived remnants produced in such mergers might be affected by convective instabilities. Those would trigger the excitation of inertial modes, providing a potential method to improve our understanding of the rotational and thermal properties of neutron stars through the analysis of the modes' imprint in the late post-merger gravitational-wave signal. In this paper we assess the detectability of those modes by injecting numerically generated post-merger waveforms into colored Gaussian noise of second-generation and future detectors. Signals are recovered using BayesWave, a Bayesian data-analysis algorithm that reconstructs them through a morphology-independent approach using series of sine-Gaussian wavelets. Our study reveals that current interferometers (i.e. the Handford-Livingston-Virgo network) recover the peak frequency of inertial modes only if the merger occurs at distances of up to 1 Mpc. For future detectors such as the Einstein Telescope, the range of detection increases by about a factor 10.