Dependence of late-time tail amplitude on binary initial conditions

Determine the dependence of the late-time gravitational-wave tail amplitude on the initial conditions of a black hole binary, in order to identify regimes in which quasinormal modes are short-lived and the tail contribution is maximized.

Background

Black hole perturbation theory predicts power-law late-time tails in gravitational radiation, but in numerical simulations these tails are difficult to isolate because quasinormal-mode ringing can persist for a long time. To make tails observable, one needs both short-lived quasinormal modes and a large tail amplitude.

While targeting small-spin remnants can reduce quasinormal-mode lifetimes, the authors emphasize that maximizing the tail amplitude is harder because the dependence of tail strength on the binary’s initial conditions is not known a priori. Subsequent perturbative/EOB insights indicate that eccentricity can enhance tails and that radial infall maximizes the effect, motivating the head-on configurations studied here. However, a general characterization of how initial data control the tail amplitude remains to be established.