Finite perturbations on Friedmann-Robertson-Walker models

By dimensional reduction of solutions of Einstein's equations in five-dimensional vacuum, two metrics are derived which can be interpreted as finite cylindrical perturbations of the solitonic type on a radiative Friedmann-Robertson-Walker (FRW) cosmological background. A linear perturbative analysis is performed and is compared with the exact nonlinear results. The metrics are transformed to perfect fluid solutions representing finite soliton perturbations on a FRW background with stiff matter. One metric contains density modes, and the other includes the coupling between density and radiative modes. 30 references