Analytic Solutions for Cosmological Perturbations in Multi-Dimensional Space-Time

TL;DR

This paper derives exact solutions for cosmological perturbations in multi-dimensional Friedmann-Robertson-Walker universes with collisionless matter, comparing them to perfect fluid models using gauge-invariant methods.

Contribution

It provides the first analytic solutions for density and anisotropic pressure perturbations in multi-dimensional cosmologies with collisionless matter, employing gauge-invariant metric potentials.

Findings

Analytic solutions for density contrast and anisotropic pressure.

Comparison between collisionless matter and perfect fluid perturbations.

Use of gauge-invariant metric potentials and finite temperature field theory.

Abstract

We obtain analytic solutions for the density contrast and the anisotropic pressure in a multi-dimensional FRW cosmology with collisionless, massless matter. These are compared with perturbations of a perfect fluid universe. To describe the metric perturbations we use manifest gauge invariant metric potentials. The matter perturbations are calculated by means of (automatically gauge invariant) finite temperature field theory, instead of kinetic theory. (Talk given at the Journ\'ees Relativistes '93, 5 -- 7 April, Brussels, Belgium)