Sasaki-Nakamura Waveforms

This work turns the Sasaki-Nakamura formalism into a usable frequency-domain pipeline for gravitational radiation from Kerr black holes. The formalism is attractive because it replaces the long-range Teukolsky radial equation with a short-range equation, but source-driven waveform calculations still require careful treatment of inhomogeneous terms and Green-function integrals.

The main ingredients are:

• a source treatment based on integration by parts, avoiding unstable direct evaluations of the distributional source;
• frequency-domain waveforms and fluxes at infinity for particles on Kerr geodesics;
• a consistent connection between the Sasaki-Nakamura variable, the Teukolsky radiation field, and the Y convention used in the broader GSN code.

The result is a stable way to compute infinity-side radiation with the Sasaki-Nakamura equation. It also gives one half of the validation picture for ISEM: the infinity flux here can be compared against the horizon-side quantities in the near-horizon work.

The implementation is part of GeneralizedSasakiNakamura.jl.

Back to Research