This talk will be delivered in hybrid form, both in person (room 223 in the Multipurpose building) and over zoom.
Professor Saleem Zaroubi
The Astrophysics Research Center, Department of Natural Sciences, The Open
University, Israel, and Kapteyn Institute, The University of Groningen, the
Netherlands
During the first billion years of its history, our Universe transformed from its pristine
primordial conditions to the galaxies and stars-filled cosmos we see around us. This
period is divided into three eras: the first, known as the Universe’s Dark Ages, and
refers to the period before the emergence of any astrophysical sources. The second,
known as the Cosmic Dawn, is distinguished by the emergence of the first
astrophysical sources of radiation (first stars) that start heating the hydrogen in the
intergalactic medium. The third, known as the Epoch of Reionization, is the period in
which the hydrogen ionization process, caused by the ultraviolet radiation emanating
from the first generations of stars and galaxies, became the main phenomenon, lasting
until the Universe is completely ionized. One of the very few probes, if not the only
one, of the first billion years, is the 21 cm radiation that emanates from the diffuse
atomic hydrogen that permeates the intergalactic medium at these eras. In this talk, I
will review the emerging field of “21 cm cosmology” and the worldwide effort that is
currently underway to observe it with radio telescopes.