Gauge invariant Boltzmann equation and the fluid limit
arXiv:0706.4383 · doi:10.1088/0264-9381/24/24/001
Abstract
This article investigates the collisionless Boltzmann equation up to second order in the cosmological perturbations. It describes the gauge dependence of the distribution function and the construction of a gauge invariant distribution function and brightness, and then derives the gauge invariant fluid limit.
36 pages