Soliton collision in cosmologies with matter

Abstract

The authors present a family of exact solutions of the four-dimensional Einstein field equations obtained by means of the application of the inverse scattering technique followed by a Kaluza-Klein dimensional reduction. They describe the collision of gravitational solitons on four-dimensional Friedmann-Robertson-Walker backgrounds with a material content consisting of a perfect fluid with a barotropic equation of state. They investigate the behaviour of the stress-energy tensor and show that the collision can form voids and halos. Applications to the Brans-Dicke theory and the problem of geodesic focusing are also considered.