Formation of topological black holes from gravitational collapse

We consider the gravitational collapse of a dust cloud in an asymptotically anti-de Sitter spacetime in which points connected by a discrete subgroup of an isometry subgroup of anti-de Sitter spacetime are identified. We find that black holes with event horizons of any topology can form from the collapse of such a cloud. The quasilocal mass parameter of such black holes is proportional to the initial density, which can be arbitrarily small. [S0556-2821(97)00120-3]. PACS number(s): 04.70.Bw, 04.20.Gz, 04.40.Nr.