Speaker
Description
I will present a mathematical and numerical investigation on primordial black hole formation from the collapse of adiabatic cosmological perturbations, describing into details the mechanism of gravitational collapse. For a radiation dominated fluid this is described by the mechanism of critical collapse. Starting from a time independent curvature profile, specified on the super horizon regime using the gradient expansion approach, I study primordial black hole formation from adiabatic cosmological perturbations. This allows to compute the threshold and the mass distribution of primordial black holes consistently with the power spectrum of cosmological perturbations obtained from inflation. This scenario can be generalised during the quark-hadron (QCD) phase transition, when the equation of state is characterised by a softening, reducing significantly the pressure gradients around the solar mass scale. This enhances the formation of primordial black holes, in the mass range of binary systems merging into a bigger black hole, emitting gravitational waves observed by LIGO/Virgo. This gives a possible interesting explanation for the signals of the LVK catalog falling into the lower mass gap, which are difficult to be explained by black holes formed from stellar collapse.
