Twofold hidden conformal symmetries of the Kerr-Newman black hole

In this paper, we suggest that there are two different individual two-dimensional conformal field theories (CFTs) holographically dual to the Kerr-Newman black hole, coming from the corresponding two possible limits---the Kerr/CFT and Reissner-Nordstr\"om/CFT correspondences, namely, there exist the Kerr-Newman/CFTs dualities. A probe scalar field at low frequencies turns out can exhibit two different two-dimensional conformal symmetries (named by J and Q pictures, respectively) in its equation of motion when the associated parameters are suitably specified. These twofold dualities are supported by the matchings of entropies, absorption cross sections, and real-time correlators computed from both the gravity and the CFT sides. Our results lead to a fascinating ``microscopic hair conjecture''---for each macroscopic hair parameter, in addition to the mass of a black hole in the Einstein-Maxwell theory, there should exist an associated holographic CFT₂ description.