THE INTERACTION OF OUTGOING AND INGOING SPHERICALLY SYMMETRICAL NULL FLUIDS

Using similarity methods, the Einstein field equations coupled to two oppositely directed null fluids for a spherically symmetric space-time are reduced to an autonomous system of three ordinary differential eq uations. The space of solutions is studied in some detail and solution s are found that represent: (i) the backscattering of an initially out going thick null fluid shell in a background gravitational held with a central naked singularity, (ii) the formation of strong space-time si ngularities by the interaction of thick null fluid shells, (iii) the i nteraction of a core of null radiation with an incoming shell of null fluid, and (iv) cosmological models of Kantowski-Sachs type with initi al and final singularities clothed by apparent horizons. (C) 1995 Amer ican Institute of Physics.