Dynamics of finite and infinite self-gravitating systems from quasi-uniform initial conditions

by Prof. Francesco Sylos Labini

Friday 16 Jan 2009, 16:00 → 18:00 Europe/Rome

Aula Corbino (Dip. di Fisica - Edificio E. Fermi)

Purely self-gravitating systems of point particles have been extensively studied in astrophysics and cosmology, mainly through numerical simulation, butunderstanding of their dynamics remains extremely limited. We describe here results of a detailed study of a simple class of cold quasi-uniform initial conditions, for both finite open systems and infinite systems. These cases illustrate well the qualitative features of the quite different dynamics observed in each case. In the finite case our study highlights the potential importance of energy and mass ejection prior to virialization, a phenomenon which has been previously overlooked. We discuss in both cases the validity of a mean-field Vlasov-Poisson description of the dynamics observed, and the question of how it should be tested for by a suitable numerical extrapolation. The explicit dependences of macroscopic results on particle number which are observed in the finite case allow one to illustrate the subtleties which may be involved in taking this limit.