Quasiequilibria in one-dimensional self-gravitating many-body systems

The microscopic dynamics of one-dimensional self-gravitating many-body systems is studied. We examine two courses of the evolution that have the isothermal or stationary water-bag distribution as initial conditions. We investigate the evolution of the systems toward thermal equilibrium. It is found that when the number of degrees of freedom of the system is increased, the water-bag distribution becomes a quasiequilibrium, and the stochasticity of the system reduces. These results suggest that the phase space of the system is effectively not ergodic and the system with large degrees of freedom approaches the near-integrable one.