Publication Date:
2014-01-29
Description:
We present a quintuply lensed z ~ 6 candidate discovered in the field of the galaxy cluster RXC J2248.7–4431 ( z ~ 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 ~ 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 ~ 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 $L_{1600}\sim 0.5L_{1600}^*$ at z = 6. We also estimate the UV slope from the observed NIR colours, finding a steep β = –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 ~ 10 8 M , subsolar metallicity ( Z 〈 0.2 Z ) and low dust content ( A V ~ 0.2–0.4).
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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