Relevance of tidal effects and post-merger dynamics for binary neutron star parameter estimation

TL;DR

This paper investigates how tidal effects and post-merger dynamics influence the accuracy of binary neutron star parameter estimation using gravitational-wave data, highlighting when these factors become significant.

Contribution

It introduces a comprehensive analysis of tidal and post-merger effects on parameter estimation, using complete waveforms and realistic simulations to assess biases.

Findings

Neglecting tidal effects causes minimal bias at low SNR and small tidal deformability.

Higher SNR or tidal deformability leads to significant parameter biases.

Post-merger effects do not impact current gravitational-wave measurements at typical SNRs.

Abstract

Measurements of the properties of binary neutron star systems from gravitational-wave observations require accurate theoretical models for such signals. However, current models are incomplete, as they do not take into account all of the physics of these systems: some neglect possible tidal effects, others neglect spin-induced orbital precession, and no existing model includes the post-merger regime consistently. In this work, we explore the importance of two physical ingredients: tidal interactions during the inspiral and the imprint of the post-merger stage. We use complete inspiral--merger--post-merger waveforms constructed from a tidal effective-one-body approach and numerical-relativity simulations as signals against which we perform parameter estimates with waveform models of standard LIGO-Virgo analyses. We show that neglecting tidal effects does not lead to appreciable measurement biases in masses and spin for typical observations (small tidal deformability and signal-to-noise ratio $\sim$ 25). However, with increasing signal-to-noise ratio or tidal deformability there are biases in the estimates of the binary parameters. The post-merger regime, instead, has no impact on gravitational-wave measurements with current detectors for the signal-to-noise ratios we consider.