Low Mach number limit for the diffusion approximation model in radiation hydrodynamics at equilibrium-diffusion regime

The low Mach number limit for the compressible viscous diffusion approximation model arising in radiation hydrodynamics is rigorously justified. For the 3-D Cauchy problem, the solutions in an equilibrium diffusion regime are shown to converge to the solutions of an incompressible Navier-Stokes equations locally and globally in time as Mach number goes to zero, when the effect of the small temperature variation upon the limit is taken into account.