Critical phenomena in spherical gravitational collapse

In general relativity, critical collapse is a phenomenon for which in dependence of the choice of some parameter of initial data, the resulting spacetimes can be regular or singular and so the evolution could finish in dispersal or in a formation of a black hole/naked singularity, respectively. Moreover, in the second case, it was found the power-law scale for the black hole masses. These phenomena in gravitational collapse were first found by Choptuik in numerical simulation of spherically symmetric massless scalar field. In the present thesis the study of these example have been extended to a wider class of models. The collapsing time and the bouncing time, in order to understand if the collapse or the bouncing happens in a finite time, have been analysed and we have proved that it is so. Moreover we have observed that also at the end of supercritical evolution the singularity is naked and so the singularity is not covered.