Non-LTE radiation hydrodynamics in PLUTO

Modeling the dynamics of most astrophysical structures requires an adequate description of the radiation-matter interaction. Several numerical (magneto)hydrodynamics codes were upgraded with a radiation module to fulfill this request. However, those among them that use either the flux-limited diffusion (FLD) or the M1 radiation moment approaches are restricted to the local thermodynamic equilibrium (LTE). This assumption may be not valid in some astrophysical cases. We present an upgraded version of the LTE radiation-hydrodynamics module implemented in the PLUTO code, originally developed by Kolb et al. (2013), which we have extended to handle non-LTE regimes. Starting from the general freq…