A Lichnerowicz equation in the Einstein-scalar field theory on non-CMC closed manifolds
Bartosz Bieganowski, Pietro d'Avenia, Jacopo Schino, Daniel Strzelecki
TL;DR
The work analyzes a Lichnerowicz-type elliptic equation arising from the Einstein–scalar constraint equations on closed manifolds with nonconstant mean curvature. It reduces the coupled constraints to a single equation for the conformal factor $u$, which contains Sobolev-supercritical and singular terms when the mean curvature is non-CMC. The authors prove the existence of a positive weak (and under extra regularity, $C^{2,\alpha}$) solution using a sub-/supersolution framework and a monotone fixed-point argument, and they derive explicit nonexistence criteria (NE1–NE5) that preclude smooth positive solutions in certain coefficient regimes. These results illuminate solvability conditions for Einstein–scalar field constraints under non-CMC data and provide tools for controlling or obstructing solutions via the data.
Abstract
In the paper, we prove the existence of a positive and essentially bounded solution to a Lichnerowicz equation in the Einstein-scalar field theory on a closed manifold with non-constant mean curvature. In particular, the non-constant mean curvature gives rise to supercritical terms in the equation, on top of singular ones. We employ a recent fixed-point argument, which involves sub- and supersolutions. Additionally, we provide several conditions on the coefficients in the equation that prevent the existence of positive classical solutions.
