Three acts.One remnant.
The waveform is not a metaphor. It is a chronology written in strain.
01
Inspiral
Two black holes orbit. Gravitational waves carry energy and angular momentum away. The orbit decays. The frequency rises. A chirp.
- Inspiral
- Merger
- Ringdown
Amplitude and time are not to scale. The tone is a pedagogical chirp, frequency-scaled into hearing, as LIGO does for public audio. Not GW231029. The three names are the standard IMR decomposition.
After ringdown, the no-hair theorems say the remnant is described by mass and spin. Charge, in astrophysics, is usually negligible.
Numerical relativity supplies the merger; black-hole perturbation theory supplies the ringdown tones (quasinormal modes). Matching them to the inspiral is how a template is born. If the ringdown overtones fit Kerr, the remnant is behaving like a rotating black hole.