From the first stars to the first black holes

We investigate the nature and origin of the first super-massive black holes at redshift larger than 5 by means of an improved version of the semi analytical model GAMETE/QSOdust. In this study, we model the formation of the progenitors (seeds) of the first super-massive black holes along host galaxies hierarchical assembly. Low-mass seed black holes (~100 Msun) form as remnants of massive (260-300 Msun), population III stars, the so-called light seeds, while intermediate mass black holes (10⁴ - 10⁵ Msun), the so-called heavy seeds, arise from the direct collapse of gas in metal poor (Z<Zcr) halos exposed to a strong H2 photo-dissociating Lyman Werner flux. I will present a detailed analysis of the role of light and heavy seeds in the formation of a ~10⁹ solar mass black hole at redshift z~6. 4, consistently modeling the evolution of the environment out of which they form and of the chemical properties (metals and dust) of their host galaxies.