Homogeneous vacua of (generalized) new massive gravity

We obtain all homogeneous solutions of new massive gravity models on S^3 and AdS_3 by extending previously known results for the cosmological topologically massive theory of gravity in three dimensions. In all cases, apart from the maximally symmetric vacua, there are axially symmetric (i.e., bi-axially squashed) as well as totally anisotropic (i.e., tri-axially squashed) metrics of special algebraic type. Transitions among the vacua are modeled by instanton solutions of 3+1 Horava-Lifshitz gravity with anisotropic scaling parameter z=4.