Frequency-domain gravitational waves from non-precessing black-hole binaries. I. New numerical waveforms and anatomy of the signal

TL;DR

This paper develops new frequency-domain gravitational wave models for non-precessing black-hole binaries, combining numerical relativity simulations with analytical approximations to improve accuracy across the entire signal.

Contribution

It introduces new numerical waveforms, calibrates models for final spin and energy, and develops a comprehensive phenomenological waveform model for non-precessing black-hole mergers.

Findings

New numerical relativity waveforms for mass ratios up to 18

Calibrated simple expressions for final spin and radiated energy

Developed an accurate merger-ringdown model based on modified Lorentzians

Abstract

In this paper we discuss the anatomy of frequency-domain gravitational-wave signals from non-precessing black-hole coalescences with the goal of constructing accurate phenomenological waveform models. We first present new numerical-relativity simulations for mass ratios up to 18 including spins. From a comparison of different post-Newtonian approximants with numerical-relativity data we select the uncalibrated SEOBNRv2 model as the most appropriate for the purpose of constructing hybrid post-Newtonian/numerical-relativity waveforms, and we discuss how we prepare time-domain and frequency-domain hybrid data sets. We then use our data together with results in the literature to calibrate simple explicit expressions for the final spin and radiated energy. Equipped with our prediction for the final state we then develop a simple and accurate merger-ringdown-model based on modified Lorentzians in the gravitational wave amplitude and phase, and we discuss a simple method to represent the low frequency signal augmenting the TaylorF2 post-Newtonian approximant with terms corresponding to higher orders in the post-Newtonian expansion. We finally discuss different options for modelling the small intermediate frequency regime between inspiral and merger-ringdown. A complete phenomenological model based on the present work is presented in a companion paper.