Construction of GCM hypersurfaces in perturbations of Kerr
Dawei Shen
TL;DR
This work advances the nonlinear stability program for Kerr by removing symmetry restrictions in the general covariant modulated (GCM) framework and constructing GCM hypersurfaces in perturbations of Kerr. It develops a rigorous procedure to concatenate a 1-parameter family of GCM spheres into a spacelike GCM hypersurface via an ODE system for mode data, then enforces additional GCM conditions through a Banach fixed-point argument. The paper provides detailed geometric setup, relies on GCM spheres from KS Kerr1, and derives precise estimates for transition functions and extrinsic quantities to ensure controlled deformations. The resulting hypersurface Σ0 and its ODE governing Ψ,Λ,underline Λ constitute a key step toward a full nonlinear Kerr stability proof by enabling decay estimates without axial symmetry assumptions.
Abstract
This is a follow-up of \cite{KS:Kerr1} on the general covariant modulated (GCM) procedure in perturbations of Kerr. In this paper, we construct GCM hypersurfaces, which play a central role in extending GCM admissible spacetimes in \cite{KS:main} where decay estimates are derived in the context of nonlinear stability of Kerr family for $|a|\ll m$. As in \cite{KS}, the central idea of the construction of GCM hypersurfaces is to concatenate a $1$--parameter family of GCM spheres of \cite{KS:Kerr1} by solving an ODE system. The goal of this paper is to get rid of the symmetry restrictions in the GCM procedure introduced in \cite{KS} and thus remove an essential obstruction in extending the results to a full stability proof of the Kerr family.
