GENERAL ROTATING BLACK-HOLES IN STRING THEORY - GREYBODY FACTORS AND EVENT HORIZONS

We derive the wave equation for a minimally coupled scalar field in th e background of a general rotating five-dimensional black hole. It is written in a form that involves two types of thermodynamic variables, defined at the inner and outer event horizon, respectively. We model t he microscopic structure as an effective string theory, with the therm odynamic properties of the left-and right-moving excitations related t o those of the horizons. Previously known solutions to the wave equati on are generalized to the rotating case, and their regime of validity is sharpened. We calculate the greybody factors and interpret the resu lting Hawking emission spectrum microscopically in several Limits. We find a U-duality-invariant expression for the effective string length that does not assume a hierarchy between the charges. It accounts for the universal low-energy absorption cross section in the general nonex tremal case.