The constraint equations for the Einstein-scalar field system on compact manifolds

TL;DR

This paper analyzes the Einstein-scalar field constraint equations on compact manifolds using the conformal method, introducing a new invariant to classify data and determine solution existence for various subclasses, encompassing several classical problems.

Contribution

It introduces a new conformal invariant that classifies initial data and determines solution existence for the Einstein-scalar field constraints on compact manifolds.

Findings

Classifies initial data into subclasses based on a new conformal invariant.

Determines solution existence for many subclasses of the Einstein-scalar field system.

Includes special cases like vacuum constraints, Yamabe, and prescribed scalar curvature problems.

Abstract

We study the constraint equations for the Einstein-scalar field system on compact manifolds. Using the conformal method we reformulate these equations as a determined system of nonlinear partial differential equations. By introducing a new conformal invariant, which is sensitive to the presence of the initial data for the scalar field, we are able to divide the set of free conformal data into subclasses depending on the possible signs for the coefficients of terms in the resulting Einstein-scalar field Lichnerowicz equation. For many of these subclasses we determine whether or not a solution exists. In contrast to other well studied field theories, there are certain cases, depending on the mean curvature and the potential of the scalar field, for which we are unable to resolve the question of existence of a solution. We consider this system in such generality so as to include the vacuum constraint equations with an arbitrary cosmological constant, the Yamabe equation and even (all cases of) the prescribed scalar curvature problem as special cases.