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

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 $\left(ξ= 0.75\right)$ induces further post-merger time-frequency peaks. Additionally we show that even mild precessing spin $\left(χ_p = 0.25\right)$ 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.