COSMOLOGICAL PRODUCTION OF CHARGED BLACK-HOLE PAIRS

We investigate the pair creation of charged black holes in a backgroun d with a positive cosmological constant. We consider C metrics with a cosmological constant, and show that the conical singularities in the metric only disappear when it reduces to the Reissner-Nordstrom-de Sit ter metric. We construct an instanton describing the pair production o f extreme black holes and an instanton describing the pair production of nonextreme black holes from the Reissner-Nordstrom de Sitter metric , and calculate their actions. There are a number of striking similari ties between these instantons and the Ernst instantons, which describe pair production in a background electromagnetic held. We also observe that the type I instanton in the ordinary C metric with zero cosmolog ical constant is actually the Reissner-Nordstrom solution.