Holographic description of AdS2 black holes

We develop the holographic renormalization of AdS(2) gravity systematically. We find that a bulk Maxwell term necessitates a boundary mass term for the gauge field and verify that this unusual term is invariant under gauge transformations that preserve the boundary conditions. We determine the energy-momentum tensor and the central charge, recovering recent results by Hartman and Strominger. We show that our expressions are consistent with dimensional reduction of the AdS(3) energy-momentum tensor and the Brown-Henneaux central charge. As an application of our results we interpret the entropy of AdS(2) black holes as the ground state entropy of a dual CFT.