Graviton in a Curved Space-Time Background and Gauge Symmetry
  Pauli-Fierz approach to description of a massless spin-2 particle is investigated in the framework of 30-component first order relativistic wave equation theory on a curved space-time background. It is shown that additional gauge symmetry of massless equations established by Pauli-Fierz can be extended only to curved space-time regions where Ricci tensor vanishes. In all such space-time models the generally covariant S=2 massless wave equation exhibits gauge symmetry property, otherwise it is not so. 
V.M. Red'kov, N.G. Tokarevskaya, V.V. Kisel
math-ph gr-qc math.MP