Observations on the holographic duals of 4-d extremal black holes

We argue that extremal black holes of N=4 Poincaré supergravity coupled to conformal matter have a quantum-exact dual 5-d description in the maximally supersymmetric extension of the Randall–Sundrum theory. This dual is a the classical, static supergravity solution describing a string with both Neveu–Schwarz and Ramond charge with respect to different antisymmetric tensor doublets. We also discuss the issue of the singularity present in a class of such supergravity solutions found by Cvetič, Lü and Pope.