The model has an "extended" Gibbs measure ft. both energy and momentum due to its non-Galilean nature. Thus, proper Langevin dynamics should have a bath that not only plays the role of a thermostat, enforcing temperature, but also of a tachostat, enforcing velocity, like a crowd walking around you!
ALT: a large crowd of people are walking down a street with a sign that says ' a ' on it
