Stringy black hole interiors

Abstract

Abstract It is well known that non-perturbative α ′ corrections to the SL(2, ℝ)/U(1) cigar geometry are described via a condensation of a Sine-Liouville operator that schematically can be written as W + + W − , where W ± describe a string with winding number ±1. This condensation leads to interesting effects in the cigar geometry that take place already at the classical level in string theory. Condensation of the analytically continued Sine-Liouville operator in the Lorentzian SL(2, ℝ)/U(1) black hole is problematic. Here, we propose that in the black hole case, the non-perturbative α ′ corrections are described in terms of an operator that can be viewed as the analytic continuation of the fusion of W + and W − . We show that this operator does not suffer from the same problem as the analytically continued Sine-Liouville operator and argue that it describes folded strings that fill the entire black hole and, in a sense, replace the black hole interior. We estimate the folded strings radiation, and show that they radiate at the Hawking temperature.