Abstract

Inspired by a similar analysis for the vacuum conformal Einstein field equations by Paetz (Ann Henri Poincaré 16:2059, 2015), in this article we show how to construct a system of quasilinear wave equations for the geometric fields associated to the conformal Einstein field equations coupled to matter models whose energy-momentum tensor has vanishing trace. In this case, the equation of conservation for the energy-momentum tensor is conformally invariant. Our analysis includes the construction of a subsidiary evolution which allows to prove the propagation of the constraints. We discuss how the underlying structure behind these systems of equations is the set of integrability conditions satisfied by the conformal field equations. The main result of our analysis is that both the evolution and subsidiary equations for the geometric part of the conformal Einstein-tracefree matter field equations close without the need of any further assumption on the matter models other that the vanishing of the trace of the energy-momentum tensor. Our work is supplemented by an analysis of the evolution and subsidiary equations associated to three basic tracefree matter models: the conformally invariant scalar field, the Maxwell field and the Yang–Mills field. As an application we provide a global existence and stability result for de Sitter-like spacetimes. In particular, the result for the conformally invariant scalar field is new in the literature.

Highlights

  • The conformal Einstein field equations are a conformal representation of the Einstein field equations which permit us to study the global properties of the solutions to equations of General Relativity by means of Penrose’s procedure of conformal compactification—see e.g. [11,15] for an entry point to the literature on the subject

  • Inspired by a similar analysis for the vacuum conformal Einstein field equations by Paetz (Ann Henri Poincaré 16:2059, 2015), in this article we show how to construct a system of quasilinear wave equations for the geometric fields associated to the conformal Einstein field equations coupled to matter models whose energy-momentum tensor has vanishing trace

  • We supplement our general analysis of the metric conformal Einstein field equations with an analysis of the evolution and subsidiary evolution equations of some of the tracefree matter models more commonly used in the literature: the Maxwell field, the Yang–Mills field and the conformally invariant scalar field

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Summary

Introduction

The conformal Einstein field equations are a conformal representation of the Einstein field equations which permit us to study the global properties of the solutions to equations of General Relativity by means of Penrose’s procedure of conformal compactification—see e.g. [11,15] for an entry point to the literature on the subject. In [17] Paetz has obtained a satisfactory hyperbolic procedure for the metric vacuum Einstein field equations which is based on the construction of second order wave equations To round up his analysis, Paetz proceeds to construct a system of subsidiary wave equations for tensorial fields encoding the conformal Einstein field equations (the so-called geometric zero-quantities) showing, in this way, the propagation of the constraints. The case of tracefree matter is of particular interest since the equation of conservation satisfied by the energy-momentum is conformally invariant; the associated equations of motion for the matter fields can, usually, be shown to possess good conformal properties—see [15], Chapter 9 It clarifies the inner structure of Paetz’s original construction by identifying the integrability conditions underlying the mechanism of the propagation of the constraints. To the best of our knowledge, these integrability conditions have not

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The metric conformal Einstein field equations with tracefree matter
Basic relations
The unphysical energy-momentum tensor
Basic properties of the conformal Einstein field equations
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An alternative equation for dabcd
The evolution system for the geometric fields
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Zero-quantities and integrability conditions
Definitions and basic properties
Properties of the zero-quantities
Some consequences of the wave equations
Integrability conditions
The subsidiary evolution system for the zero-quantities
Construction of the subsidiary system
Equation for 3abc
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Propagation of the constraints
Gauge considerations
Conformal gauge source functions
Generalised harmonic coordinates and the reduced Ricci operator
The reduced wave operator
Summary: gauge reduced evolution equations
Propagation of the gauge
The Bach tensor
Wave equations for the gauge subsidiary variables
Evolution equations for the matter fields
The conformally invariant scalar field
Auxiliary fields and the evolution equations
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Subsidiary equations
Summary
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The Yang–Mills field
Basic equations
Evolution equations for the Yang–Mills fields
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Applications
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10 Concluding remarks
Full Text
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