Density growth in Kantowski-Sachs cosmologies with cosmological constant

Abstract

In this work the growth of density perturbations in Kantowski-Sachs cosmologies with a positive cosmological constant is studied, using the 1+3 and 1+1+2 covariant formalisms. For each wave number we obtain a closed system for scalars formed from quantities that are zero on the background and hence are gauge-invariant. The solutions to this system are then analyzed both analytically and numerically. In particular the effects of anisotropy and the behaviour close to a bounce in the cosmic scale factor are considered. We find that typically the density gradient in the bouncing directions experiences a local maximum at or slightly after the bounce.

33 pages, 17 pictures

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• On the Interaction Between Electromagnetic, Gravitational, and Plasma Related Perturbations on LRS Class II Spacetimes
• Skyrme Fluid in Anisotropic Universe
• Perturbations of Kantowski-Sachs models with a cosmological constant
• Density perturbation and cosmological evolution in the presence of magnetic field in $f(R)$ gravity models