Regularity estimates on harmonic eigenmaps with arbitrary number of coordinates

Abstract

We revisit the well-established regularity estimates on harmonic maps on surfaces to question their independence with respect to the dimension of the target manifold. We are mainly interested in harmonic maps into target ellipsoids, that we call Laplace harmonic eigenmaps. These maps are related to critical metrics in the context of eigenvalue optimization. The tools that we gather here are useful to handle convergence of almost critical metrics via Palais-Smale sequences of (almost harmonic) eigenmaps. They could also be a preliminary step for a general regularity theory for critical points of infinite combinations of eigenvalues.