Astrophysics Colloquium--Galaxy Evolution in the First Billion Years: How HST has Revolutionized Our View of the Universe (Speaker: Steven Finkelstein, University of Texas)
Abstract: The field of high-redshift galaxy evolution has experience an explosion over the past three years, thanks to the installation of the infrared-sensitive Wide Field Camera 3 on the Hubble Space Telescope. In the first few months after the servicing mission, numerous papers were published detailing the discovery of the first robust galaxy samples at z = 7 and 8, with the most distant galaxies dating only 500 million years from the Big Bang. Since that time, new deep and wide area surveys, such as the HST Multi-cycle Treasury Program CANDELS, has allowed us to take a detailed look into the properties of these galaxies. These data allow us to probe into the epoch when we expect to see galaxies vigorously building up their stellar, chemical, and dust reservoirs. I will discuss my ongoing work examining these enigmatic galaxies, first on understanding the colors of these galaxies, from which we have learned about the build-up of dust in the universe, as well as the possible presence of primordial stars. I will also show how we use these galaxies to probe the reionization of the intergalactic medium, which was likely ending around this epoch. Finally, I will detail key tests for the future, including those which can only be done with the James Webb Space Telescope.