Seminarium "Teoria cząstek elementarnych i kosmologia"

Among all the possible candidates for Dark Matter, one appealing example is a population of Primordial Black Holes, which could have been borne by various processes in the early stages of the Universe. In this talk, I will investigate the formation of such objects as the result of the collapse of energy density fluctuations originating from supercooled first-order phase transitions. I will present the results of a simplified approach, where the energy density fluctuations are evolved within the limit of flat FRW Universe. These results let us identify how the parameters of the phase transition, such as temperature and transition speed, influence the spectrum and total population of Primordial Black Holes. Additionally, I will show how energy density fluctuations modify the Gravitational Wave signals as the production of secondary Gravitational Waves is induced. Finally, we will discuss the latest results, where the full covariant formalism of cosmological perturbation is introduced and show how it impacts the production of Primordial Black Holes and Gravitational Waves.