On asymptotically harmonic manifolds of negative curvature

Philippe Castillon (1) , Andrea Sambusetti (2)

1 I3M - Institut de Mathématiques et de Modélisation de Montpellier
2 UNIROMA - Università degli Studi di Roma "La Sapienza" = Sapienza University [Rome]

We study asymptotically harmonic manifolds of negative curvature, without any cocompactness or homogeneity assumption. We show that asymptotic harmonicity provides a lot of information on the asymptotic geometry of these spaces: in particular, we determine the volume entropy, the spectrum and the relative densities of visual and harmonic measures on the ideal boundary. Then, we prove an asymptotic analogue of the classical mean value property of harmonic manifolds, and we characterize asymptotically harmonic manifolds, among Cartan-Hadamard spaces of strictly negative curvature, by the existence of an asymptotic equivalent $\tau(u)\ex^{Er}$ for the volume-density of geodesic spheres (with $\tau$ constant in case $DR_M$ is bounded). Finally, we show the existence of a Margulis function, and explicitly compute it, for all asymptotically harmonic manifolds.

Mots clés: asymptotic geometry; Asymptotically harmonic manifolds

Domaines: Géométrie différentielle [math.DG]

Philippe Castillon, Andrea Sambusetti. On asymptotically harmonic manifolds of negative curvature. Mathematische Zeitschrift, 2014, 277 issue: 3-4, p. 1049-1072. ⟨10.1007/s00209-014-1293-7⟩. ⟨hal-00678222⟩