We clarify the higher-dimensional origin of a class of dyonic gaugings of D = 4 N = 8 supergravity recently discovered, when the gauge group is chosen to be ISO(7). This dyonically-gauged maximal supergravity arises from consistent truncation of massive IIA supergravity on S 6 , and its magnetic coupling constant descends directly from the Romans mass. The critical points of the supergravity uplift to new AdS4 massive type IIA vacua. We identify the corresponding CFT3 duals as superChern-Simons-matter theories with simple gauge group SU(N ) and level k given by the Romans mass. In particular, we find a critical point that uplifts to the first explicit N = 2 AdS4 massive IIA background. We compute its free energy and that of the candidate dual Chern-Simons theory by localisation to a solvable matrix model, and find perfect agreement. This provides the first AdS4/CFT3 precision match in massive type IIA string theory.

We construct consistent Kaluza-Klein reductions of D = 11 supergravity to four dimensions using an arbitrary seven-dimensional Sasaki-Einstein manifold. At the level of bosonic fields, we extend the known reduction, which leads to minimal N = 2 gauged supergravity, to also include a multiplet of massive fields, containing the breathing mode of the Sasaki-Einstein space, and still consistent with N = 2 supersymmetry. In the context of flux compactifications, the Sasaki-Einstein reductions are generalizations of type IIA SU(3)-structure reductions which include both metric and form-field flux and lead to a massive universal tensor multiplet. We carry out a similar analysis for an arbitrary weak G 2 manifold leading to an N = 1 supergravity with massive fields. The straightforward extension of our results to the case of the seven-sphere would imply that there is a four-dimensional Lagrangian with N = 8 supersymmetry containing both massless and massive spin two fields. We use our results to construct solutions of M-theory with non-relativistic conformal symmetry.

Motivated by its well defined higher dimensional origin, a detailed study of D = 4 N = 8 supergravity with a dyonically gauged ISO(7) = SO(7) R 7 gauge group is performed. We write down the Lagrangian and describe the tensor and duality hierarchies, focusing on an interesting subsector with closed field equations and supersymmetry transformations. We then truncate the N = 8 theory to some smaller sectors with N = 2 and N = 1 supersymmetry and SU(3), G 2 and SO(4) bosonic symmetry. Canonical and superpotential formulations for these sectors are given, and their vacuum structure and spectra is analysed. Unlike the purely electric ISO(7) gauging, the dyonic gauging displays a rich structure of vacua, all of them AdS. We recover all previously known ones and find a new N = 1 vacuum with SU(3) symmetry and various non-supersymmetric vacua, all of them stable within the full N = 8 theory.