Maximum velocity for wave propagation in a relativistic rarefied gas

Considering the hyperbolic symmetric system of moments associated with the relativistic Boltzmann-Chernikov equation and closed through procedures of Extended Thermodynamics, we determine numerically the maximum characteristic wave velocity for degenerate and non-degenerate gases. As predicted by recent results, this velocity increases monotonically with respect to the number of moments and tends asymptotically to the speed of light. We show that many moments are often required to approach with a good approximation the speed of light. The dependence of the maximum characteristic wave velocity on the properties of the materials is also investigated and it turns out that it depends significantly on the chemical potential only in the case of Fermions gases. Received April 24, 1999