Analytic modelling of tidal effects in the relativistic inspiral of binary neutron stars

TL;DR

This paper presents the longest general-relativistic simulations of binary neutron star inspirals with different compactnesses and demonstrates that a calibrated tidal EOB model accurately reproduces the numerical waveforms up to merger, improving gravitational wave templates.

Contribution

It introduces the longest simulations of equal-mass binary neutron stars with different compactnesses and calibrates a tidal EOB model to match these waveforms within numerical errors.

Findings

Calibrated tidal EOB model matches numerical waveforms up to merger.

Numerical phase errors are approximately ±0.24 radians over 22 GW cycles.

Third post-Newtonian Taylor-T4 approximant shows significant dephasing.

Abstract

To detect the gravitational-wave (GW) signal from binary neutron stars and extract information about the equation of state of matter at nuclear density, it is necessary to match the signal with a bank of accurate templates. We present the two longest (to date) general-relativistic simulations of equal-mass binary neutron stars with different compactnesses, C=0.12 and C=0.14, and compare them with a tidal extension of the effective-one-body (EOB)model. The typical numerical phasing errors over the $\simeq 22$ GW cycles are $\Delta \phi\simeq \pm 0.24$ rad. By calibrating only one parameter (representing a higher-order amplification of tidal effects), the EOB model can reproduce, within the numerical error, the two numerical waveforms essentially up to the merger. By contrast, the third post-Newtonian Taylor-T4 approximant with leading-order tidal corrections dephases with respect to the numerical waveforms by several radians.