SÉMINAIRE DU GRECO
"Primordial black holes, critical collapse and structure formation in the early universe" 

Ilia Musco 

The wellknown process of critical collapse has been shown to arise within an expanding universe, in the context of sphericallysymmetric simulations of primordial black hole formation. Cosmological perturbations, of the type expected to have come from inflation, have been shown to collapse after horizon crossing and give rise to primordial black holes if the perturbation amplitude is larger than a threshold which depends on the equation of state and the perturbation profile. I will review some of the main aspects of this scenario, presenting results coming from my personal simulations. One of the key aspect is the the method used to impose initial conditions during the regime of the linear growth of cosmological perturbations in the early universe, corresponding to a pure growing mode, when perturbation lengthscales are much larger than the cosmological horizon. In this regime, pressure gradients are secondorder effects and the curvature perturbation can be characterized by a constant profile used to perturb all the other quantities. This method to impose initial conditions in a cosmological settings, is interesting beyond the PBH scenarios, to study more in general the formation of structure in LCDM early universe.


jeudi 13 juin 2013  14:00 Salle Entresol Daniel Chalonge, Institut d'Astrophysique de Paris 
