Perturbations of Kantowski-Sachs models with a cosmological constant

TL;DR

This paper studies how small disturbances evolve in Kantowski-Sachs cosmological models with a positive cosmological constant, using covariant and harmonic methods to analyze scalar, vector, and tensor perturbations.

Contribution

It introduces a comprehensive covariant framework for analyzing perturbations in Kantowski-Sachs models with a cosmological constant, including scalar, vector, and tensor modes.

Findings

Reduced perturbation equations to six evolution equations.

Included general scalar, vector, and tensor modes.

Applied harmonic decomposition for analysis.

Abstract

We investigate perturbations of Kantowski-Sachs models with a positive cosmological constant, using the gauge invariant 1+3 and 1+1+2 covariant splits of spacetime together with a harmonic decomposition. The perturbations are assumed to be vorticity-free and of perfect fluid type, but otherwise include general scalar, vector and tensor modes. In this case the set of equations can be reduced to six evolution equations for six harmonic coefficients.