CONFORMAL SYMMETRY INHERITANCE WITH COSMOLOGICAL CONSTANT

A study is made of space-times satisfying the Einstein field equations with a nonzero cosmological constant and admitting a conformal Killing vector (CKV), xi(a), which is such that the Lie derivative of the energy-momentum tensor in the direction of xi(a) is zero. This condition is necessary, but not sufficient, to ensure that the physical quantities associated with the energy-momentum tensor inherit the CKV symmetry. It is shown that this condition leads to two classes of space-times, each of which may be regarded as generalizations of the de Sitter space-times. The possible physical interpretations of these models are discussed.