In this article we classify expanding homogeneous Ricci solitons up to
dimension 5, according to their presentation as homogeneous spaces. We obtain
that they are all isometric to solvsolitons, and this in particular implies
that the generalized Alekseevskii conjecture holds in these dimensions. In
addition, we prove that the conjecture holds in dimension 6 provided the
transitive group is not semisimple.Comment: 20 pages, 3 tables; Appendix by Jorge Laure
