Observing mergers of non-spinning black-hole binaries

TL;DR

This paper analyzes the merger phase of non-spinning black-hole binaries using an analytic waveform model, examining how mass ratio affects observational signals and waveform degeneracy, with implications for gravitational wave detection.

Contribution

It introduces a study of non-spinning black-hole mergers across various mass ratios using an analytic model calibrated with numerical data, highlighting waveform similarities and degeneracies.

Findings

Waveform phasing is similar across different mass ratios.

Merger signal-to-noise ratios vary with mass ratio and detector.

Degeneracy in mass ratio can be significant for moderate-mass-ratio mergers.

Abstract

Advances in the field of numerical relativity now make it possible to calculate the final, most powerful merger phase of binary black-hole coalescence for generic binaries. The state of the art has advanced well beyond the equal-mass case into the unequal-mass and spinning regions of parameter space. We present a study of the nonspinning portion of parameter space, primarily using an analytic waveform model tuned to available numerical data, with an emphasis on observational implications. We investigate the impact of varied mass ratio on merger signal-to-noise ratios (SNRs) for several detectors, and compare our results with expectations from the test-mass limit. We note a striking similarity of the waveform phasing of the merger waveform across the available mass ratios. Motivated by this, we calculate the match between our 1:1 (equal mass) and 4:1 mass-ratio waveforms during the merger as a function of location on the source sky, using a new formalism for the match that accounts for higher harmonics. This is an indicator of the amount of degeneracy in mass ratio for mergers of moderate-mass-ratio systems.