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

We report the discovery of seven strongly lensed Lyman-break galaxy (LBG) candidates at z similar to 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 24.0AB (26 sigma) in the WFC3/IRF160W band, making it 0.2 mag brighter than the z(850)-dropout candidate recently reported behind the Bullet Cluster and 0.7 mag brighter than the previously brightest known z similar to 7.6 galaxy, A1689-zD1. With a cluster magnification of similar to 9, this source has an intrinsic magnitude of H-160 = 26.4 AB, a strong z(850) - J(125) break of 1.7 mag, and a photometric redshift of z similar to 6.7. Additionally, we find six other bright LBG candidates with H-160-band magnitudes of 24.9-26.4, photometric redshifts z similar to 6.4 - 8.8, and magnifications mu similar to 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(9) M-circle dot, stellar ages 5-180 Myr, and star formation rates similar to 7.8M(circle dot) yr(-1),and low reddening with AV <= 0.7. The source-plane reconstruction of the exceptionally bright candidate A1703-zD1 exhibits an extended structure, spanning similar to 4 kpc in the z similar to 6.7 source plane, and shows three resolved star-forming knots of radius r similar to 0.4 kpc.