THROUGH THE LOOKING GLASS: BRIGHT, HIGHLY MAGNIFIED GALAXY CANDIDATES AT z ∼ 7 BEHIND A1703

• Published in: The Astrophysical journal 2012-03, Vol.747 (1), p.1-10
• Main Authors: Bradley, L D, Bouwens, R J, Zitrin, A, Smit, R, Coe, D, d, H C, Zheng, W, Illingworth, G D, Benitez, N, Broadhurst, T J
• Format: Article
• Language: English
• Subjects: Arrays; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CAMERAS; Clusters; Field cameras; GALAXIES; GALAXY CLUSTERS; Hubble Space Telescope; MASS; Photometry; Projectiles; Reconstruction; RED SHIFT; STARS; TELESCOPES
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1088/0004-637X/747/1/3

We report the discovery of seven strongly lensed Lyman-break galaxy (LBG) candidates at z ~ 7 detected in Hubble Space Telescope Wide Field Camera 3 (WFC3) imaging of A1703. The brightest candidate, called A1703-zD1, has an observed (lensed) magnitude of 24.0 AB (26[sigma]) in the WFC3/IR F160W band, making it 0.2 mag brighter than the z sub(850)-dropout candidate recently reported behind the Bullet Cluster and 0.7 mag brighter than the previously brightest known z ~ 7.6 galaxy, A1689-zD1. With a cluster magnification of ~9, this source has an intrinsic magnitude of H sub(160) = 26.4 AB, a strong z sub(850) - J sub(125) break of 1.7 mag, and a photometric redshift of z ~ 6.7. Additionally, we find six other bright LBG candidates with H sub(160)-band magnitudes of 24.9-26.4, photometric redshifts z ~ 6.4 - 8.8, and magnifications mu ~ 3-40. Stellar population fits to the Advanced Camera for Surveys, WFC3/IR, and Spitzer/Infrared Array Camera data for A1703-zD1 and A1703-zD4 yield stellar masses (0.7 - 3.0) x 10 super(9) M, stellar ages 5-180 Myr, and star formation rates ~7.8 M yr super(-1), and low reddening with A sub(V) [< or =, slant] 0.7. The source-plane reconstruction of the exceptionally bright candidate A1703-zD1 exhibits an extended structure, spanning ~4 kpc in the z ~ 6.7 source plane, and shows three resolved star-forming knots of radius r ~ 0.4 kpc.