Explain late-time QNM/tail amplitude comparability

Explain why amplitudes of quasi-normal modes and tail terms become comparable only at late times in BBH simulations—rather than shortly after merger—and determine whether this feature is tied to global boundary conditions such as the no-incoming-radiation condition at the horizon.

Background

Linear perturbations on Kerr backgrounds generically include normal modes, QNMs, and tails. Numerical relativity commonly observes late-time signals dominated by QNMs; tails appear to emerge much later, despite general expectations that tail amplitudes could compete earlier.

The review suggests this may be linked to global boundary conditions (e.g., no-incoming radiation at the horizon), and calls for a deeper theoretical account of the funneling of initial data into QNM-dominated regimes.