Multipole moments on the common horizon in a binary-black-hole simulation

Understand

We construct the covariantly defined multipole moments on the common horizon of an equal-mass, non-spinning, quasicircular binary-black-hole system.

• We see a strong correlation between these multipole moments and the gravitational waveform.
• We find that the multipole moments are well described by the fundamental quasinormal modes at sufficiently late times.
• For each multipole moment, at least two fundamental modes of different $\ell$ are detectable in the best model.