Intersections of S-branes with waves and monopoles

In this thesis we study static and time dependent solutions of supergravity theories. We discuss p-branes, plane waves, Kaluza-Klein monopoles and time dependent S-brane solutions. We then proceed to describe the Kaluza-Klein dimensional reduction procedure and discuss how theories in lower dimensions can be obtained from theories in higher dimensions. As the main result of this thesis we present new solutions of supergravity theories involving intersections of S-branes with plane waves and Kaluza-Klein monopoles. We find that configurations involving intersections of S-branes with waves are restricted in that the wave can be placed only on the transverse space of the S-brane and the transverse space must be flat. We also find that a larger number of configurations involving intersections of S-branes with Kaluza-Klein monopoles exist. As a potential application we consider adding an S-brane to ten dimensional solutions that describe extremal black holes in lower dimensions, which in turn could lead to black holes in a time dependent background. However, we find that in these configurations the conditions imposed on the integration constants render the metric time independent.