Feedback in the Early Universe and X-ray reionization
Massimo Ricotti (The University of Maryland)
In this talk I will discuss galaxy feedback processes and their role in
regulating the formation of the first sources of ionization. In recent
years Population III stars have been a very popular candidate to explain
the early reionization measured by WMAP. I will argue that they are
probably unimportant for reionization and propose a different ionization
scenario in which a prolonged partial ionization by X-rays emitted by
accreting black holes precedes stellar reionization at z = 6. The X-ray
reionization model can also be used to constrain the existence of
Primordial Black holes more massive than 0.1-1 solar masses. The
(preliminary) results are of interest in constraining the nature of
the dark matter and MACHOs.
