Raffaella Schneider - November 27, 2015

Growing the first super-massive black holes: head start by heavy seeds or by
super-Eddington accretion?

The formation, assembly history, and environmental impact of the first super
massive black holes (BH) at z ~ 6 are still hotly debated topics in cosmic
structure formation.
Seed BHs must form at very high redshift, z > 10, if they start small 
(< 10^4 Msun)and are accreting no faster than the Eddington rate. 
BH seeds with masses ~100 Msun may naturally arise at these early epochs 
from the collapse of Pop III stars.

An alternative, direct route to the formation of ~ 10^5 Msun BHs in the 
first galaxies involves the rapid collapse of metal-free gas irradiated by 
a strong UV flux, which suppresses H2 formation and fragmentation into stars. 
Yet, fragmentation is inevitable if high-redshift dark matter halos are already
enriched with at least trace amounts of metals and dust produced by prior star
formation in their progenitors. In this talk, I will present some recent
work on these early phases of galaxy and BH mass assembly, using independent
constraints inferred from stellar archeology and observations of high-z
galaxies.