Inelastic clump collision model for non-Gaussian velocity distribution in molecular clouds

Non-Gaussian velocity distribution in star forming region is reproduced by inelastic clump collision model. We numerically calculated the evolution of inelastic hard spheres in sheared flow, which corresponds to cloud clumps in differential galactic rotation. This system fluctuates largely around equilibrium state, creating clusters with inelastic collisions and destroying them with shear motion. The fluctuation makes spheres have non-Gaussian velocity distribution with nearly exponential tail. How far from Gaussian distribution depends upon coefficient of restitution, which can produce the variety of degree of deviation from Gaussian among regions.