The nonlinear stability of rotationally symmetric spaces with low regularity

We consider rotationally symmetric spaces with low regularity, which we regard as integral currents spaces or manifolds with Sobolev regularity that are assumed to have nonnegative scalar curvature. Relying on the flat distance and on Sobolev norms, we establish several nonlinear stability estimates about the “distance” between a rotationally symmetric manifold and the Euclidean space, which are stated in terms of the ADM mass of the manifold. Importantly, we make explicit the dependencies and scales involved in this problem, particularly the ADM mass, the depth, and the CMC reference hypersurface. Several notions of independent interest are introduced in the course of our analysis, including the notion of depth of a manifold and a scaled version of the flat-distance, the D-flat distance as we call it, which involves the diameter of the manifold. Finally we prove a compactness theorem for sequences of regions with uniformly bounded depth, whose outer boundaries have fixed area and an upper bound on Hawking mass.