Measuring quasi-normal mode amplitudes with misaligned binary black hole ringdowns

Understand

In recent work, we examined how different modes in the ringdown phase of a binary coalescence are excited as a function of the final plunge geometry.

• At least in the large mass ratio limit, we found a clean mapping between angles describing the plunge and the amplitude of different quasi-normal modes (QNMs) which constitute the ringdown.
• In this study, we use that mapping to construct a waveform model expressed as a sum of QNMs where the mode amplitudes and phases are determined by the source plunge parameters.
• We first generate a large number of calibration waveforms and interpolate between fits of each mode amplitude and phase up to $\ell \leq 8$ and $\ell - |m| \leq 4$.