Strongly pseudoconvex domains as subvarieties of complex manifolds

TL;DR

This paper establishes existence and approximation results for complex subvarieties normalized by strongly pseudoconvex Stein domains, using Morse theory and Levi eigenvalues, extending classical theorems in complex geometry.

Contribution

It provides new sufficient conditions based on Morse indices and Levi eigenvalues for the existence of such subvarieties in complex manifolds.

Findings

Conditions are sharp and cannot be generally weakened.

Optimal results for subvarieties in complements of compact submanifolds with Griffiths positive normal bundle.

Generalizes classical theorems of Remmert, Bishop, and Narasimhan in the projective case.

Abstract

In this paper (a sequel to B. Drinovec Drnovsek and F. Forstneric, Holomorphic curves in complex spaces, Duke Math. J. 139 (2007), 203-253) we obtain existence and approximation results for closed complex subvarieties that are normalized by strongly pseudoconvex Stein domains. Our sufficient condition for the existence of such subvarieties in a complex manifold is expressed in terms of the Morse indices and the number of positive Levi eigenvalues of an exhaustion function on the manifold. Examples show that our condition cannot be weakened in general. Optimal results are obtained for subvarieties of this type in complements of compact complex submanifolds with Griffiths positive normal bundle; in the projective case these results generalize classical theorems of Remmert, Bishop and Narasimhan concerning proper holomorphic maps and embeddings to complex Euclidean spaces.