On the temperature dependence of the absorption cross-section for black holes in string theory

We study the low frequency absorption cross-section of spherically symmetric nonextremal d-dimensional black holes. In the presence of alpha' corrections, this quantity must have an explicit dependence on the Hawking temperature of the form 1/T-H. This property of the low frequency absorption cross-section is shared by the D1-D5 system from type IIB superstring theory already at the classical level, without alpha' corrections. We apply our formula to the simplest example, the classical d-dimensional Reissner-Nordstrom solution, checking that the obtained formula for the cross-section has a smooth extremal limit. We also apply it for a d-dimensional Tangherlini-like solution with alpha'(3) corrections.