The decoupling of scalar-modes from a linearly perturbed dust-filled Bianchi type I model
arXiv:1504.01900 · doi:10.1088/0256-307X/31/1/010402
Abstract
We study linear perturbations about a dust filled Bianchi Type I model with the vorticity set to zero. In comparison to linear perturbations about FLRW models, modes of perturbations about Bianchi type I models are coupled. We find that the tensor that represents the background shear needs to be degenerate in order for the scalar-mode perturbations to decouple from the rest of the flow.
4 pages