Inhomogeneous deformations of Einstein solvmanifolds

For each non-flat, unimodular Ricci soliton solvmanifold $(\mathsf{S}_0,g_0)$, we construct a one-parameter family of complete, expanding, gradient Ricci solitons that admit a cohomogeneity one isometric action by $\mathsf{S}_0$. The orbits of this action are hypersurfaces homothetic to $(\mathsf{S}_0,g_0)$. These metrics are asymptotic at one end to an Einstein solvmanifold. In the one-parameter family, exactly one metric is Einstein, and exactly one has orbits that are isometric to $(\mathsf{S}_0,g_0)$.