Conformal Vector Fields and Null Hypersurfaces

Abstract We give conditions for a conformal vector field to be tangent null hypersurface. particularize two important cases: Killing and closed field. In the first case, we obtain result ensuring that hypersurface is horizon. second one, gives rise foliation of manifold by totally umbilical hypersurfaces with constant mean curvature which can spacelike, timelike or null. prove several results ensure leaf this foliation.