Recent results on z~7-10 galaxies

Due to an increase in efficiency by a factor about 40, the installation of the WFC3/IR camera on the Hubble Space Telescope revolutionized our knowledge about galaxies in the reionization epoch. From the combination of our extremely deep HUDF09 survey with additional wide-area imaging it became possible to identify large samples of galaxies at z~7-8, and we were even able to find one first galaxy at z~10, only 500 Myr after the Big Bang.

We recently created a new multi-color image of the Hubble Ultra Deep Field (called XDF), including all the available data in the optical and NIR that was taken over this field with HST over the last decade. This new image provides the deepest view of the universe ever and is shown below. The full release can be found on hubblesite.org

source: hubblesite.org

Some recent research highlights are shown below. For more information see also www.firstgalaxies.org and our new page: xdf.ucolick.org.

The Lyman Break Galaxy UV luminosity function at z~8 (~650 Myr after the Big Bang) as derived from the combination of the full WFC3/IR data available around the GOODS-South field. The dark blue points are based on the 75 sources from the HUDF09, ERS and CANDELS surveys, covering a total of ~160 arcmin2. The best-fit Schechter luminosity function is shown as dark blue line. This curve has an extremely steep faint-end slope of alpha=-2.06, indicating that ultra-faint dwarf galaxies were very abundant and likely were the drivers of cosmic reionization. The green and dark red colored lines represent the UV luminosity functions at later cosmic epochs (1 Gyr at z~6 and 1.6 Gyr at z~4), showing how the galaxy population builds up during this time. All the information on this plot and how it is derived can be found in Oesch et al. 2012b.

An image of the only z~10 galaxy candidate we found in the NIR data over the Hubble Ultra Deep Field. For sources at such early times, the neutral hydrogen in the inter-galactic medium absorbs all the light at wavelengths shorter than ~1.3 microns. Therefore, we can only see such galaxies in the H-band (right most panel). The fact that we only found one such source indicates that the number density of galaxies with star-formation rates of more than 1 Msol/yr is evolving rapidly within less than 200 Myr from z~8 to z~10. All about our z~10 galaxy search can be found in Oesch et al. 2012a and Bouwens et al. 2011.

A link to all my first-author publications is: Link (ADS)