Prospects for distinguishing dynamical tides in inspiralling binary neutron stars with third generation gravitational-wave detectors

TL;DR

Third generation gravitational-wave detectors could enable the measurement of dynamical tides in neutron star inspirals, providing insights into neutron star matter and higher-order tidal effects, especially for high-frequency signals.

Contribution

This study assesses the potential to measure dynamical tides in neutron star mergers with future detectors, highlighting the dependence on neutron star properties and the ability to probe higher-order effects.

Findings

Approximately 50 out of 10,000 neutron star binaries may have measurable dynamical tides.

F-mode frequencies can be measured to within a few hundred Hz for GW170817-like signals.

Dynamical tides offer a way to test neutron star models and universal relations.

Abstract

Tidal effects in gravitational-wave (GW) observations from binary neutron star mergers have the potential to probe ultra-dense matter and shed light on the unknown nuclear equation of state of neutron stars. Tidal effects in inspiralling neutron star binaries become relevant at GW frequencies of a few hundred Hz and require detectors with exquisite high-frequency sensitivity. Third generation GW detectors such as the Einstein Telescope or Cosmic Explorer will be particularly sensitive in this high-frequency regime, allowing us to probe neutron star tides beyond the adiabatic approximation. Here we assess whether dynamical tides can be measured from a neutron star inspiral. We find that the measurability of dynamical tides depends strongly on the neutron star mass and equation of state. For a semi-realistic population of 10,000 inspiralling binary neutron stars, we conservatively estimate that on average $\mathcal{O}(50)$ binaries will have measurable dynamical tides. As dynamical tides are characterised not only by the star's tidal deformability but also by its fundamental ($f$-) mode frequency, they present a possibility of probing higher-order tidal effects and test consistency with quasi-universal relations. For a GW170817-like signal in a third generation detector network, we find that the stars' $f$-mode frequencies can be measured to within a few hundred Hz.