Steady asymptotic equilibria in conformal relativistic fluids

When one considers a shock wave in the frame where is at rest, on either side has steady flow which converges to equilibrium away from shock. However, hydrodynamics unable describe this if asymptotic velocity higher than characteristic speed of theory. We obtain an exact solution for decay rate conformal fluid kinetic theory under relaxation time approximation, and compare it two hydrodynamic schemes, accounting second moments distribution function thus equivalent, small deviations limit, Israel-Stewart framework, another both third moments. While still having finite speed, model significant improvement first.