Consistent subsectors of maximal supergravity and wrapped M5-branes

A new family of $D=4$ $\mathcal{N}=8$ gauged supergravities is introduced, consisting in a mixture of Scherk-Schwarz and dyonic CSO gaugings that involves the trombone scaling symmetry. A specific theory in this class is shown to admit supersymmetric anti-de Sitter vacua, argued to be related to various wrapped M5-brane configurations. The mass spectrum of these vacua within our maximal theory is computed, extending previous results in smaller gauged supergravity models, and shown to exhibit some exotic features due to the trombone gauging. These vacua are obtained as solutions of certain subsectors of our $\mathcal{N}=8$ supergravity. Such subsectors in turn arise by consistent truncation of the parent maximal supergravity to the invariant fields under specific groups that are not contained in the $\mathcal{N}=8$ gauge group. Prompted by these and other similar subtruncations recently considered, we formalise sufficient conditions that allow any maximal supergravity to be truncated consistently to invariant subsectors thereof when the invariance group is not necessarily contained in the $\mathcal{N}=8$ gauge group.