Dr. Rennan Barkana (Tel Aviv)

Date: Oct. 29, 2006

Title: The Next Great Cosmological Probe: 21-cm Emission from the Era
of the First Galaxies

Abstract:

Cosmologists have studied on the one hand the cosmic microwave
background from the early universe, and on the other hand, galaxies
and quasars that formed much more recently. This leaves an unknown
frontier, from redshift 6 up to 1000, during which the first stars
formed and subsequently heated and ionized the cosmic gas. Several
international efforts are underway to measure fluctuations in the
redshifted 21-cm emission from neutral hydrogen at these
redshifts. This new observational probe promises to reveal much about
physics in the very early universe as well as previously unobserved
astrophysical epochs. The talk will show that while numerical
simulations increasingly contribute to the field, powerful analytical
models dominate our understanding of when the first stars formed and
how they subsequently affected the cosmic gas and its expected
signature in 21-cm radiation.