A new formalism for radiative transfer

The departure from the thermodynamic equilibrium is chosen as a new distribution function for thermal photons. In the resulting transport equation, the 'source term' is mainly determine by space and time gradients of temperatures on one hand, by a 'universal' frequency spectrum on the other hand. The heat conduction is directly included, so, it does not require any special time-splitting. Comparisons with literature are displayed and numerically complicated cases are analyzed. (author)