CLASH: z similar to 6 young galaxy candidate quintuply lensed by the frontier field cluster RXC J2248.7-4431

Monna, A.; Seitz, S.; Greisel, N.; Eichner, T.; Drory, N.; Postman, M.; Zitrin, A.; Coe, D.; Halkola, A.; Suyu, S. H.; Grillo, C.; Rosati, P.; Lemze, D.; Balestra, I.; Snigula, J.; Bradley, L.; Umetsu, K.; Koekemoer, A.; Kuchner, U.; Moustakas, L.; Bartelmann, M.; Benitez, N.; Bouwens, R.; Broadhurst, T.; Donahue, M.; Ford, H.; Host, O.; Infante, L.; Jimenez-Teja, Y.; Jouvel, S.; Kelson, D.; Lahav, O.; Medezinski, E.; Melchior, P.; Meneghetti, M.; Merten, J.; Molino, A.; Moustakas, J.; Nonino, M.; Zheng, W.
2014
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
DOI
10.1093/mnras/stt2284
We present a quintuply lensed z similar to 6 candidate discovered in the field of the galaxy cluster RXC J2248.7-4431 (z similar to 0.348) targeted within the Cluster Lensing and Supernova survey with Hubble (CLASH) and selected in the deep Hubble Space Telescope (HST) frontier fields survey. Thanks to the CLASH 16-band HST imaging, we identify the quintuply lensed z similar to 6 candidate as an optical dropout in the inner region of the cluster, the brightest image having mag(AB) = 24.8 +/- 0.1 in the f105w filter. We perform a detailed photometric analysis to verify its high-z and lensed nature. We get as photometric redshift z(ph) similar to 5.9, and given the extended nature and NIR colours of the lensed images, we rule out low-z early-type and galactic star contaminants. We perform a strong lensing analysis of the cluster, using 13 families of multiple lensed images identified in the HST images. Our final best model predicts the high-z quintuply lensed system with a position accuracy of 0.8 arcsec. The magnifications of the five images are between 2.2 and 8.3, which leads to a delensed UV luminosity of L-1600 similar to 0.5L(1600)* at z=6. We also estimate the UV slope from the observed NIR colours, finding a steep beta = -2.89 +/- 0.38. We use singular and composite stellar population SEDs to fit the photometry of the high-z candidate, and we conclude that it is a young (age <300 Myr) galaxy with mass of M similar to 10(8) M-circle dot, subsolar metallicity (Z < 0.2 Z(circle dot)) and low dust content (A(V) similar to 0.2-0.4).