The Dirichlet-to-Neumann Map for Poincaré-Einstein Fillings
Samuel Blitz, A. Rod Gover, Jarosław Kopiński, Andrew Waldron
Abstract
We study the non-linear Dirichlet-to-Neumann map for the Poincaré-Einstein filling problem. For even dimensional manifolds the range of this non-local map is described in terms of a rank two "Dirichlet-to Neumann tensor" along the boundary determined by the Poincaré-Einstein metric. This tensor is proportional to the variation of renormalized volume along a path of Poincaré-Einstein metrics. We construct natural "Dirichlet-to-Neumann hypersurface invariants" that are conformally invariant and recover all Dirichlet-to-Neumann tensors. We give an explicit formula for these hypersurface invariants and use a new vanishing result for odd order $T$-curvatures to show that they are the unique, natural conformal hypersurface invariant of transverse order equaling the boundary dimension. We also construct such conformally invariant Dirichlet-to-Neumann hypersurface invariants for Poincaré-Einstein fillings for odd dimensional manifolds with conformally flat boundary.
