Time-frequency structure in the post-merger binary black hole gravitational wave signal

TL;DR

This paper explores the complex time-frequency features of post-merger gravitational wave signals from binary black holes, revealing how spins influence the signal structure and supporting a link to horizon geometry.

Contribution

It extends previous studies by analyzing the effects of aligned and precessing spins on post-merger signals using waveform models, highlighting new features induced by spin.

Findings

Strong aligned spin induces additional post-merger peaks.

Precessing spin affects the distribution of radiative power.

Results support correlation between post-merger signals and horizon geometry.

Abstract

Gravitational wave signals from asymmetric binary black hole systems have been shown to exhibit additional chirps beyond the primary merger chirp in the post-merger region of the time-frequency domain. These secondary post-merger chirps correlate to the evolving geometry of the common horizon that forms as the binary merges and were previously studied through numerical relativity simulation in a zero-spin regime. In this work, we investigate the post-merger time-frequency structure in systems with both aligned and precessing spin using widely available waveform models. We find that the inclusion of strong aligned spin $\left(\xi = 0.75\right)$ induces further post-merger time-frequency peaks. Additionally we show that even mild precessing spin $\left(\chi_p = 0.25\right)$ strongly affects the distribution of post-merger radiative power across the celestial sky of the final black hole. Our results support the theory of a correlation between the post-merger signal and horizon geometry.