« Some aspects of Vlasov-Poisson equations » |
Stéphane Colombi |
Dark matter or stars in galaxies are ensembles of particles that can be approximated with a self-gravitating, collisionless fluid, of which the dynamics is described by Vlasov-Poisson equations. I will study some properties of these equations and how they are solved numerically with the traditional N-body method and direct solvers using ``semi-Lagrangian" methods and sophisticated computational geometry techniques. Focusing here on the dynamical evolution of single objects, I will study what happens for various systems, evolving from an initially warm or initially cold state. The concept of mean field limit will be approached through comparisons between N-body and Vlasov codes that will show that it is sometimes difficult if not nearly impossible to disentangle numerical from physical effects. I will discuss as well theoretical predictions, in particular the early evolution of dark matter proto-halos using perturbation theory and ``post-collapse" perturbation theory. |
vendredi 8 septembre 2017 - 11:00 Amphithéâtre Henri Mineur, Institut d'Astrophysique de Paris |
Page web du séminaire / Seminar's webpage |