Young Galaxy Candidates in the Hubble Frontier Fields. I. Abell 2744

Understand

We report the discovery of 24 Lyman-break candidates at 7<z<10.5, in the Hubble Frontier Fields (HFF) imaging data of Abell 2744 (z=0.308), plus Spiter/IRAC data and archival ACS data.

• The sample includes a triple image system with a photometric redshift of z~7.4.
• This high redshift is geometrically confirmed by our lens model corresponding to deflection angles that are 12% larger than the lower-redshift systems used to calibrate the lens model at z=2.019.
• The majority of our high-redshift candidates are not expected to be multiply lensed given their locations in the image plane and the brightness of foreground galaxies, but are magnified by factors of ~1.3-15, so that we are seeing further down the luminosity function than comparable deep field imaging.