On electrostatic manifolds with boundary
Stanislav Demurov, Vladimir Medvedev
TL;DR
This work introduces electrostatic manifolds with boundary as a natural extension of static manifolds by incorporating a nonzero electric field, yielding a coupled system for the static potential $V$ and the electric field $E$. It establishes critical geometric consequences, including that the boundary is totally umbilical and the zero set $\Sigma=V^{-1}(0)$ is totally geodesic, with scalar curvature $R_g=2|E|^2+2\Lambda$, and it connects these manifolds to variational principles via a functional $\mathcal{F}$. The authors develop a framework for uniqueness of non-compact electrostatic manifolds with boundary, defining quasi-local photon spheres and using RN manifolds as canonical models, and they prove rigidity theorems that classify such geometries under natural asymptotic and boundary conditions. They further relate the geometry of $\Sigma$ to global properties through a Pohozaev-type identity, deriving sharp area bounds for $\Sigma$ and clarifying when $\Sigma$ is a sphere or a disk. The appendices provide explicit Reissner–Nordström computations, including photon-sphere analysis in RN spacetimes, unifying the static and electrostatic settings within a common variational and geometric framework.
Abstract
Static manifolds with boundary were recently introduced by Cruz and Vitório in the context of the prescribed scalar curvature problem in a manifold with boundary with prescribed mean curvature. This kind of manifold is also interesting from the point of view of the general theory of relativity. In this article, we introduce electrostatic manifolds with boundary as a natural generalization of static manifolds with boundary in the presence of a non-zero electric field. We study the geometry of the zero-level set of the potential and its connection to the global properties of electrostatic manifolds with boundary. In particular, we establish some rigidity theorems for the 3-dimensional Euclidean ball and for the Reissner-Nordström manifold.
