Speaker
Prof.
Rennan Barkana
(Tel Aviv University)
Description
A major frontier area in cosmology is cosmic reionization, the key
epoch in which the intergalactic hydrogen throughout the universe was
reionized after having recombined in the early universe. Despite
uncertainties about the sources of radiation at early times, it is
widely assumed that prior to reionization the cosmic gas must have
been pre-heated to well over the temperature of the cosmic microwave
background. We show instead that the universe is likely to heat
significantly only during reionization. This dramatically changes the
expectations for currently operating as well as planned radio
telescope arrays aimed at detecting the 21-cm spectral line of atomic
hydrogen at high redshift. Observing the resulting signatures would
provide a remarkable probe of some of the earliest stars (likely
responsible for reionization) and black holes (responsible for the
heating).
Primary author
Prof.
Rennan Barkana
(Tel Aviv University)
