Long-range correlations in self-gravitatingN-body systems

Abstract

Observed self-gravitating systems reveal often fragmented, non-equilibrium structures that feature char- acteristic long-range correlations. However, models accounting for non-linear structure growth are not always consistent with observations and a better understanding of self-gravitating N-body systems appears necessary. Because unstable gravitating systems are sensitive to non-gravitational perturbations, we study the eect of dierent dissipative factors as well as dierent small and large scale boundary conditions on idealized N-body systems. We nd, in the interval of negative specic heat, equilibrium properties diering from theoretical pre- dictions made for gravo-thermal systems, substantiating the importance of microscopic physics and the lack of consistent theoretical tools to describe self-gravitating gas. Also, in the interval of negative specic heat, yet outside of equilibrium, unforced systems fragment and establish transient long-range correlations. The strength of these correlations depends on the degree of granularity, which shows that the mass and force resolution should be coherent. Finally, persistent correlations appear in model systems subject to an energy flow.