We classify noncompact homogeneous spaces which are Einstein and asymptotically harmonic. This completes the classification of Riemannian harmonic spaces in the homogeneous case: Any simply connected homogeneous harmonic space is flat, or rank-one symmetric, or a nonsymmetric Damek-Ricci space. Independently, Y. Nikolayevsky has obtained the latter classification under the additional assumption of nonpositive sectional curvatures [N2].
Abstract. Let M be a Hadamard manifold of dimension 3 whose sectional curvature satisfies −b 2 ≤ K ≤ −a 2 < 0 and whose curvature tensor satisfies ∇R ≤ C for suitable constants 0 < a ≤ b and C ≥ 0. We show that M is of constant sectional curvature provided M is asymptotically harmonic. This was previously only known if M admits a compact quotient.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.