Plenary Talks

4) Tues 13.30-14.15
Galaxies in the First Billion Years
I will review our rapidly improving knowledge of the early formation and
evolution of galaxies during the first billion years of cosmic time. In
recent years, dramatic observational progress with Hubble, Spitzer, Vista,
and spectrographs on 8-m telescopes has enabled us to chart the rise of the
early galaxy population back to redshifts z ~ 10, and to deduce the basic
physical properties of galaxies at these early times. We have also been able
to estimate the contribution of young galaxies to the re-ionization of the
Universe, and I will show that the inferred progress
of re-ionization is now in excellent agreement with new measurements of the
Thomson scattering optical depth from microwave background observations with
Planck. Finally I will discuss the exciting prospects for further
breakthroughs over the next ~ 5 years. ALMA now has the capability to answer
outstanding questions over the prevalence of cosmic dust and metals at early
times, while JWST can reveal galaxies out to z ~ 20, should they exist, and
enable the rest-frame optical study of the young Universe. The first
galaxies have not yet been seen, but there are good theoretical and
observational reasons to believe that we may uncover "first light" in the
coming decade.
James Dunlop