Tsukuba Uchu Forum

7th Uchu Forum

First Cosmic Light

Andrea Ferrara

Scuola Normale Superiore


The appearence of the first stars when the universe was only 100 Myr old marked the Cosmic Dawn and the occurrence of a number of physical effects (cosmic reionization, intergalactic medium metal enrichment, black hole formation, and galaxy formation) which are now entering the realm of the observability and are strongly governed by a complex network of feedback processes. These feedback effects due to massive stars and supernovae in the first objects are shown to regulate galaxy formation/evolution and, particularly, the metal enrichment of the intergalactic medium. They are particularly relevant as it is believed that the Initial Mass Function of the first stars was very heavy, thus favoring the formation of massive objects which end their lives as supernovae, or most likely, in even more gigantic explosions which could be connected with high energy events as gamma ray bursts and TeV-neutrino emission. I will review these physical processes comparing in detail the two scenarios of pre- vs. late- reionization and propose a number of experiments which could help solving this puzzling issue.