Near-Equality of the Penrose Inequality for Rotationally Symmetric Riemannian Manifolds

This article is the sequel to Lee and Sormani (Stability of the Positive Mass Theorem for Rotationally Symmetric Riemannian Manifolds, 2011. Preprint), which dealt with the near-equality case of the Positive Mass Theorem. We study the near-equality case of the Penrose Inequality for the class of complete asymptotically flat rotationally symmetric Riemannian manifolds with nonnegative scalar curvature whose boundaries are outermost minimal hypersurfaces. Specifically, we prove that if the Penrose Inequality is sufficiently close to being an equality on one of these manifolds, then it must be close to a Schwarzschild space with an appended cylinder, in the sense of Lipschitz distance. Since the Lipschitz distance bounds the intrinsic flat distance on compact sets, we also obtain a result for intrinsic flat distance, which is a more appropriate distance for more general near-equality results, as discussed in Lee and Sormani (Stability of the Positive Mass Theorem for Rotationally Symmetric Riemannian Manifolds, 2011. Preprint).