Non-equilibrium-diffusion limit of the compressible Euler radiation model

We justify rigorously the non-equilibrium-diffusion limit of the compressible Euler model coupled with a radiative transfer equation arising in radiation hydrodynamics. For general initial data, we establish the uniform existence of the solution to the coupled model in $\mathbb{T}^{3}$ and prove the convergence of the solutions to the limiting system in the nonequilibrium-diffusion regime. Moreover, the initial layer for the radiative density is constructed to get the strong convergence in $L^\infty$ norm.