Striking the right tone: toward a self-consistent framework for measuring black hole ringdowns

Understand

The ringdown portion of a binary black hole merger consists of a sum of modes, each containing an infinite number of tones that are exponentially damped sinusoids.

• In principle, these can be measured as gravitational-waves with observatories like LIGO/Virgo/KAGRA, however in practice it is unclear how many tones can be meaningfully resolved.
• We investigate the consistency and resolvability of the overtones of the quadrupolar $\ell = m = 2$ mode by starting at late times when the gravitational waveform is expected to be well-approximated by the $\ell m n = 220$ tone alone.
• We present a Bayesian inference framework to measure the tones in numerical relativity data.