Silent universes with a cosmological constant

TL;DR

This paper investigates silent universe models with a positive cosmological constant, revealing solutions that differ from the zero-L case, especially when one eigenvalue of the expansion tensor is zero.

Contribution

It provides the first explicit solutions for non-degenerate silent universes with a positive cosmological constant, expanding understanding beyond the L=0 case.

Findings

Solutions exist for L > 0, unlike the L=0 case.

General solutions are derived for specific eigenvalue conditions.

The study highlights differences in universe models with non-zero cosmological constant.

Abstract

We study non-degenerate (Petrov type I) silent universes in the presence of a non-vanishing cosmological constant L. In contrast to the L=0 case, for which the orthogonally spatially homogeneous Bianchi type I metrics most likely are the only admissible metrics, solutions are shown to exist when L is positive. The general solution is presented for the case where one of the eigenvalues of the expansion tensor is 0.