Talk detail

Participant	Bradley, Michael
Institution	Dept. of Physics, Umeå University - Dept. of Physics, Umeå University - Umeå - Umeå - Sweden

Session	TC3	Accepted	Yes	Order	4	Time	15:00 - 15:15
Talk	Oral abstract	Title	Perturbations of Kantowski-Sachs models with a cosmological constant
Co-authors	Z. Keresztes, M. Forsberg, M. Bradley, P.K.S. Dunsby, L.Á. Gergely
Abstract	Vorticity-free perturbations of Kantowski-Sachs (KS) models with cosmological constant are considered. These can undergo an anisotropic bounce where the universe changes from a contracting to an expanding phase. A simple argument showing that an isotropic bouncing universe is excluded by observations does not hold for KS models. Hence it is of interest to study the evolution and propagation of perturbations and their possible effects on observables, like the Sachs-Wolfe effect. To do this we use the gauge invariant 1+3 and 1+1+2 covariant splits of spacetime. 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 propagation equations for six independent variables.