Higher-spin currents and thermal flux from Hawking radiation

Quantum fields near black hole horizons can be described in terms of an infinite set of $d=2$ conformal fields. In this paper, by investigating transformation properties of general higher-spin currents under a conformal transformation, we reproduce the thermal distribution of Hawking radiation in both cases of bosons and fermions. As a by-product, we obtain a generalization of the Schwarzian derivative for higher-spin currents.