Holomorphic functions of slow growth on nested covering spaces of compact manifolds

Abstract

Let Y be an infinite covering space of a projective manifold M in P^N of dimension n geq 2. Let C be the intersection with M of at most n-1 generic hypersurfaces of degree d in P^N. The preimage X of C in Y is a connected submanifold. Let phi be the smoothed distance from a fixed point in Y in a metric pulled up from M. Let O_phi(X) be the Hilbert space of holomorphic functions f on X such that f^2 e^(-phi) is integrable on X, and define O_phi(Y) similarly. Our main result is that (under more general hypotheses than described here) the restriction O_phi(Y) to O_phi(X) is an isomorphism for d large enough. This yields new examples of Riemann surfaces and domains of holomorphy in C^n with corona. We consider the important special case when Y is the unit ball B in C^n, and show that for d large enough, every bounded holomorphic function on X extends to a unique function in the intersection of all the nontrivial weighted Bergman spaces on B. Finally, assuming that the covering group is arithmetic, we establish three dichotomies concerning the extension of bounded holomorphic and harmonic functions from X to B.