Horizons in Robinson-Trautman spacetimes
Jacek Tafel · 2009
We exhibit properties of past quasi-local horizons in vacuum Robinson-Trautman spacetimes.Trapped surfaces have to intersect the surface r = 2m, which cannot be null unless g is the Schwarzschild metric.The only Robinson-Trautman metric admitting a past nonexpanding horizon is the Schwarzschild metric and the C-metric.