Probing ∼ L* Lyman-break galaxies at z≈ 7 in GOODS-South with WFC3 on Hubble Space Telescope.

We analyse recently acquired near-infrared Hubble Space Telescope imaging of the Great Observatories Origins Deep Survey (GOODS)-South field to search for star-forming galaxies at . By comparing Wide Field Camera 3 (WFC3) m Y-band images with Advanced Camera for Surveys (ACS) z-band ( m) images, we identify objects with colours consistent with Lyman-break galaxies at . This new data cover an area five times larger than that previously reported in the WFC3 imaging of the Hubble Ultra Deep Field and affords a valuable constraint on the bright end of the luminosity function. Using additional imaging of the region in the ACS B, V and i bands from GOODS v2.0 and the WFC band, we attempt to remove any low-redshift interlopers. Our selection criteria yields six candidates brighter than , of which all except one are detected in the ACS z-band imaging and are thus unlikely to be transients. Assuming all six candidates are at this implies a surface density of objects brighter than of , a value significantly smaller than the prediction from luminosity function. This suggests continued evolution of the bright end of the luminosity function between and 7, with number densities lower at higher redshift. [ABSTRACT FROM AUTHOR]