Euclidean Black Saddles and AdS4 Black Holes

The entropy of a class of asymptotically-AdS4 black holes can be reproduced by the partition function of the dual ABJM theory via localization. However, establishing this match requires a particular extremization over field theory parameters. This begs the question: what are the bulk dual geometries when we do not extremize in the field theory? In this talk, I will show that these bulk duals are smooth Euclidean geometries with finitely-capped throats. These geometries generically have no clear interpretation in Lorentzian signature, but when their throat becomes infinitely long they become black holes with an AdS2 near-horizon geometry. For any set of field theory parameters whose extremization is compatible with a black hole, we find a large family of Euclidean geometries whose on-shell action reproduces the ABJM partition function exactly, without the need to extremize,thus establishing a more complete understanding of AdS4/CFT3 holography.