Sharp bottom spectrum and scalar curvature rigidity

Abstract: We prove a sharp upper bound on the bottom spectrum of Beltrami Laplacian on geometrically contractible Riemannian manifolds with scalar curvature lower bound, and then characterize the distribution of the scalar curvature when the equality holds. Moreover, we prove a scalar curvature rigidity theorem if the manifold is the universal cover of a closed hyperbolic manifold.