  We study the stimulated scattering instabilities of an intense linearly
polarized electromagnetic wave (EMW) in a relativistic plasma with degenerate
electrons. Starting from a relativistic hydrodynamic model and the Maxwell's
equations, we derive coupled nonlinear equations for low-frequency electron and
ion plasma oscillations that are driven by the EMW's ponderomotive force. The
nonlinear dispersion relations are then obtained from the coupled nonlinear
equations which reveal stimulated Raman scattering (SRS), stimulated Brillouin
scattering (SBS), and modulational instabilities (MIs) of EMWs. It is shown
that the thermal pressure of ions and the relativistic degenerate pressure of
electrons significantly modify the characteristics of SRS, SBS, and MIs.
