Violent and mild relaxation of an isolated self-gravitating uniform and spherical cloud of particle

by Francesco Sylos Labini

Thursday 24 Oct 2013, 16:00 → 18:00 Europe/Rome

Aula Rasetti (Dip. di Fisica - Edificio G. Marconi)

The gravitational relaxation process acting during the collapse of a self-gravitating and isolated cloud of particles is the fundamental physical mechanism underlying the formation of virialized structures both in astrophysical and cosmological contexts. These structures, although never reach thermodynamical equilibrium, represent long-lived states whose lifetime diverge with the number of system particles. . The understanding of the relaxation process should eventually explain the density profiles observed in the simulations of both isolated and non isolated self-gravitating! systems and of the luminosity profiles of globular clusters and elliptical galaxies. We firstly discuss the dynamics of an isolated cloud of particles and then we consider the cosmological case. In this latter case the evolution such a structure represents a useful toy model to test the accuracy of a cosmological N-body code in the non linear regime. We show that the density profile of the virialized structure can be strongly affected by numerical artifacts and that the Navarro Frenk White density profile can be originated by numerical problems.
(Si tratta di un seminario di contenuto astrofisico e anche di fisica statistica).