Determination of equilibrium parameters of the Marle model for polyatomic gases

The BGK model is a relaxation-time approximation of the celebrated Boltzmann equation, and the Marle model is a direct extension of the BGK model in a relativistic framework. In this paper, we introduce the Marle model for polyatomic gases based on the Jüttner distribution devised in [Ann. Phys., 377, (2017), 414–445], and show the existence of a unique set of equilibrium parameters of the Jüttner distribution.