Comparison of high-accuracy numerical simulations of black-hole binaries with stationary phase post-Newtonian template waveforms for Initial and Advanced LIGO

TL;DR

This study evaluates the accuracy of post-Newtonian gravitational wave templates against numerical simulations for black-hole binaries, proposing improved frequency cutoffs and phase terms to enhance detection effectiveness for LIGO detectors.

Contribution

It introduces optimized frequency cutoffs and phase inclusion strategies for post-Newtonian templates, improving match quality with numerical waveforms for initial and advanced LIGO.

Findings

Higher frequency integration improves template-signal overlaps.

Including 3.5 pN order phase terms enhances template accuracy.

Proposed strategies achieve near-optimal overlaps across mass ranges.

Abstract

We study the effectiveness of stationary-phase approximated post-Newtonian waveforms currently used by ground-based gravitational-wave detectors to search for the coalescence of binary black holes by comparing them to an accurate waveform obtained from numerical simulation of an equal-mass non-spinning binary black hole inspiral, merger and ringdown. We perform this study for the Initial- and Advanced-LIGO detectors. We find that overlaps between the templates and signal can be improved by integrating the match filter to higher frequencies than used currently. We propose simple analytic frequency cutoffs for both Initial and Advanced LIGO, which achieve nearly optimal matches, and can easily be extended to unequal-mass, spinning systems. We also find that templates that include terms in the phase evolution up to 3.5 pN order are nearly always better, and rarely significantly worse, than 2.0 pN templates currently in use. For Initial LIGO we recommend a strategy using templates that include a recently introduced pseudo-4.0 pN term in the low-mass ($M \leq 35 \MSun$) region, and 3.5 pN templates allowing unphysical values of the symmetric reduced mass $\eta$ above this. This strategy always achieves overlaps within 0.3% of the optimum, for the data used here. For Advanced LIGO we recommend a strategy using 3.5 pN templates up to $M=12 \MSun$, 2.0 pN templates up to $M=21 \MSun$, pseudo-4.0 pN templates up to $65 \MSun$, and 3.5 pN templates with unphysical $\eta$ for higher masses. This strategy always achieves overlaps within 0.7% of the optimum for Advanced LIGO.