On geometric properties of holomorphic isometries between bounded symmetric domains
Shan Tai Chan
TL;DR
This work analyzes holomorphic isometries from the complex unit ball into irreducible bounded symmetric domains under Bergman-type metrics, revealing a rigid geometric structure of their images. By constructing a bounded balanced convex domain $D_f$ and a surjective holomorphic submersion $\widetilde{\pi}_f:D_f\to D$, the authors show that $f$ behaves as a holomorphic section with a holomorphic splitting of tangent spaces, enabling a precise description of how affine-linear sections are mapped. They establish the existence of isometries whose images are graphs of holomorphic maps, and they develop a general submersion framework that yields holomorphic retractions, leaves in holomorphic foliations, and complete-intersection results for the image submanifolds. Furthermore, the paper develops a robust theory of non-degeneracy for the associated system of functional equations, including invariance under automorphisms and criteria linking linear degeneracy to FE degeneracy, with implications for the rigidity of unit-disk to bounded symmetric domain isometries. The results illuminate the geometric and analytic structure of holomorphic isometries and connect complex-analytic foliation theory with Bergman-geometry of bounded symmetric domains.
Abstract
We study holomorphic isometries between bounded symmetric domains with respect to the Bergman metrics up to a normalizing constant. In particular, we first consider a holomorphic isometry from the complex unit ball into an irreducible bounded symmetric domain with respect to the Bergman metrics. In this direction, we show that images of (nonempty) affine-linear sections of the complex unit ball must be the intersections of the image of the holomorphic isometry with certain affine-linear subspaces. We also construct a surjective holomorphic submersion from a certain subdomain of the target bounded symmetric domain onto the complex unit ball such that the image of the holomorphic isometry lies inside the subdomain and the holomorphic isometry is a global holomorphic section of the holomorphic submersion. This construction could be generalized to any holomorphic isometry between bounded symmetric domains with respect to the \emph{canonical Kähler metrics}. Using some classical results for complex-analytic subvarieties of Stein manifolds, we have obtained further geometric results for images of such holomorphic isometries.
