TARGET SPACE DUALITY AND STRINGY BLACK-HOLES

Target space duality symmetry of the SL(2, IR)/U(1) background leads to stringy properties of the black hole. For a Euclidean space-time the semi-infinite cigar is transformed to an infinite funnel. High and low temperatures of the black hole are related. For a Lorentzian space-time, duality interchanges regions I and V in the Kruskal-Szekeres coordinates, that is, duality exchanges the horizon with the singularity. As a result, a signal can be sent out of the singularity. Such a signal is associated with the string winding modes. The mass of the black hole and the consequence of a tachyon disturbance are discussed.