New Gowdy-symmetric vacuum and electrovacuum solutions

TL;DR

This paper introduces a new family of inhomogeneous cosmological models with complex causal structures, derived using soliton theory, and extends these solutions from vacuum to electrovacuum cases.

Contribution

It constructs a 4-parameter family of solutions that generalize previous models, providing new insights into their properties and causal structures, including electrovacuum extensions.

Findings

Models exhibit regularity and singularities within the maximal globally hyperbolic region.

Presence of Cauchy horizons with both closed and non-closed null generators.

Extension of solutions from vacuum to electrovacuum with similar properties.

Abstract

We construct a 4-parameter family of inhomogeneous cosmological models, which contains two recently derived 3-parameter families as special cases. The corresponding exact vacuum solution to Einstein's field equations is obtained with methods from soliton theory. We also study properties of these models and find that they combine all interesting features of both earlier solution families: general regularity within the maximal globally hyperbolic region, particular singular cases in which a curvature singularity with a directional behaviour forms, a highly non-trivial causal structure, and Cauchy horizons whose null generators can have both closed or non-closed orbits. In the second part of the paper, we discuss the generalization from vacuum to electrovacuum. Moreover, we also present a family of exact solutions for that case and study its properties.