3D ${\tau }_{RR}$-minimization in AdS${}_4$ gauged supergravity

In this paper we propose the identification in AdS4 N = 2 gauged supergravity of the coefficient ${\tau }_{RR}$ of 3D N = 2 SCFTs. We constraint the structure of this function in supergravity by combining the results from unitarity, holography and localization. We show that our conjectured function is minimized by the exact R-charge, corresponding to a gravitational attractor for the scalars in the special geometry. We identify this mechanism with the supergravity dual of the ${\tau }_{RR}$-minimization. We check this proposal in the ABJM model, comparing with the expectations from localization and the AdS/CFT duality. We comment also on some possible relations with the black hole microstate counting, recently obtained from the application of localization techniques.