Homogeneous Hypersurfaces in 4-dimensional Thurston Geometries with 4-dimensional Isometry Group

Abstract

We classify, up to conjugacy, the 3-dimensional subalgebras of the Lie algebras associated with the 4-dimensional Thurston geometries whose isometry groups have dimension 4. Since homogeneous hypersurfaces arise as orbits of subgroups of the isometry group acting transitively on the ambient space, we determine all such subgroups and describe their corresponding orbits, thereby obtaining a classification of the homogeneous hypersurfaces, up to ambient isometries, and we study the geometry of the orbit foliations in these geometries.