Primordial Black Hole Formation in Bouncing Cosmology

The phenomenology of primordial black holes (PBHs) physics, and the associated PBH abundance constraints, can be used in order to probe the early-universe evolution. In this talk, I will firstly discuss the realisation of PBHs in the context of bouncing cosmology in general. As a specific example, I will then focus on the bounce realization within F(R) modified gravity and investigate the corresponding PBH behavior. In particular, in this work, we calculate the energy density power spectrum at horizon crossing time as a function of the involved theoretical parameters, and then we extract the PBH abundance in the context of peak theory, considering the non-linear relation between the density contrast and the comoving curvature perturbation, as well as the critical collapse law for the PBH masses. We calculate the PBH mass function, and the PBH abundance at formation time as a function of the model parameters, namely the bounce parameter and the Hubble parameter (the energy scale) at the transition time from the bounce to the radiation dominated epoch. Upon full parameter analysis, we obtain very interesting constraints on the model parameters leading to significant PBH production.