GLOBAL STRUCTURE OF ROBINSON-TRAUTMAN RADIATIVE SPACE-TIMES WITH COSMOLOGICAL CONSTANT

Robinson-Trautman radiative space-times of Petrov type II with a nonva nishing cosmological constant Lambda and mass parameter m>0 are studie d using analytical methods. They are shown to approach the correspondi ng spherically symmetric Schwarzschild-de Sitter or Schwarzschild-anti -de Sitter solution at large retarded times. Their global structure is analyzed, and it is demonstrated that the smoothness of the extension of the metrics across the horizon, as compared with the case Lambda=0 , can increase for Lambda>0 and decreases for Lambda<0. For the extrem e value 9 Lambda m(2)=1, the extension is smooth but nonanalytic. This case appears to be the first example of a smooth but nonanalytic hori zon. The models with Lambda>0 exhibit explicitly the cosmic no-hair co njecture under the presence of gravitational waves.