Boundedness and decay for the Teukolsky equation on Kerr in the full subextremal range $|a|<M$: physical space analysis

TL;DR

This paper proves that solutions to the Teukolsky equation on subextremal Kerr black holes remain bounded and decay over time, extending previous frequency-based estimates to physical space analysis.

Contribution

The authors upgrade frequency estimates to physical space, demonstrating boundedness and decay of solutions for the Teukolsky equation on Kerr backgrounds.

Findings

Solutions are bounded in time.

Solutions decay in time.

Results hold for the full subextremal range |a|<M.

Abstract

This paper concludes the study, initiated by the authors in arXiv:2007.07211, of the Teukolsky equation of spin $\pm 1$ and spin $\pm 2$ on Kerr backgrounds in the full subextremal range of parameters $|a| < M$. In our previous arXiv:2007.07211, we obtained uniform-in-frequency estimates for the ODEs governing separable solutions to the Teukolsky equation. In this paper, by adapting the techniques developed by the first author with Dafermos and Rodnianski for scalar waves, we show that our ODE estimates can be upgraded to estimates for the Teukolsky PDE. In particular, we conclude the proof that solutions of the Teukolsky equation on subextremal Kerr arising from regular initial data remain bounded and decay in time.