Harmonic Maps of Surfaces Approaching the Boundary of Moduli Space and Eliminating Bubbling

Abstract

The limit of energies of a sequence of harmonic maps as their annular domains approach the boundary of moduli space depends upon the boundary point approached. The infinite energy case is associated with limits of images containing ruled surfaces. The finite energy case yields a limit of images, under a suitable topology, with a union of discs and straight line segments. Generalization to higher numbers of boundary components shows that minimal surfaces union straight line segments can still be achieved, and that the configuration of straight line segments depends on the direction of approach of domain conformal classes to the boundary point of domain moduli space. Bubbling can occur in variable ways according to the metric representatives of the conformal classes of domains. A method is given whereby bubbling can be eliminated yielding a point-wise limit of maps with image limit containing a surface union straight line segments.