Exploring the high-redshift Universe
The First Galaxies: A View from HST and Spitzer
Guido Roberts-Borsani
R. Bouwens (Leiden), P. Oesch (Yale), I. Labbé (Leiden), P. van Dokkum (Yale), R. Smit (Durham), G. Illingworth (UC Santa Cruz), Richard Ellis (UCL/ESO), Adi Zitrin (Caltech), Dan Stark (Arizona), Stephen Wilkins (Sussex), Nicolas Laporte (UCL)
University College London
Since the installation of the Wide Field Camera 3 (WFC3) instrument on the Hubble Space Telescope (HST), an increasing number of high redshift galaxy candidates have been identified by means of their photometric properties, with > 700 probable galaxies identified at z∼7-8 and another 10-15 candidates identified even further out at z∼9-11. However, the entire enterprise of finding especially bright galaxies at z≥7 has been limited by the availability of sufficiently deep, multi-wavelength near-infrared data over wide areas of the sky. As Y-band observations are not available over the full CANDELS program to perform a standard Lyman-break selection of z>7 galaxies, we employ an alternate strategy using deep Spitzer/IRAC data. We identify z∼7.1-9.1 galaxies by selecting z >~6 galaxies from the HST CANDELS data that show quite red IRAC [3.6]−[4.5] colors, indicating strong [OIII]+Hβ lines in the 4.5μm band. Applying this selection criterium over the full ~900 arcmin^2 of the CANDELS survey, we identify 4 unusually bright (H160,AB ~7.5. All 4 candidates have been spectroscopically confirmed - with 2 of them breaking the redshift record in the process - with the derived photometric redshifts in excellent agreement with the spectroscopic redshifts, thereby validating our selection criteria.


09:00 - 10:30
EX - LT2 (200)