CLASH: z ∼ 6 young galaxy candidate quintuply lensed by the frontier field cluster RXC J2248.7−4431

Abstract

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

A free-form mass model of the Hubble Frontier Fields cluster AS1063 (RXC J2248.7−4431) with over one hundred constraints

“…Our integrated mass is in good agreement with other estimates given in Richard et al (2014) and Zitrin et al (2015) from very different parametric based models. Comparing our results with the values found in the literature within 250 kpc, we obtain M (< 250kpc) = (2.97 ± 0.09) × 10 14 whereas Monna et al (2014) and Johnson et al (2014) find slightly lower masses of (2.67 ± 0.08) × 10 14 and (2.68 0.03 −0.05 ) × 10 14 , respectively, and Caminha et al (2015a) finds a closer value to ours of (2.9 ± 0.02) × 10 14 . The lower masses found by Monna et al (2014) and Johnson et al (2014) may be due in part to a lack of spectroscopic information for some systems leading to an underestimation of the total mass.…”

“…There is general agreement that the mass distribution has a symmetric relaxed form with an obvious large-scale elongation . This large-scale elongation is aligned with the major axis of a prominent central BCG Monna et al 2014;Richard et al 2014;Zitrin et al 2015), having a similar elongation. This elongation extends well beyond the virial radius of the cluster (Gruen et al 2013), but with an azimuthally averaged large scale massive profile that fits well the NFW form out to a radius of 2 Mpc/h (Umetsu et al 2015).…”

“…Among the systems identified in the literature, system 12 in Table A1 contains 5 counterimages (Balestra et al 2013;Boone et al 2013;Bradley et al 2014;Monna et al 2014;Caminha et al 2015a). One of the images is close to the BCG and although possibly a real counterimage, we do not use it as a constraint bacause other possible images exist in the vicinity of the central image 12.5 predicted in this vicinity.…”

“…To date, ∼ 20 multiply lensed galaxies have been reliably identified Richard et al 2014;Caminha et al 2015a) (see also the recent results from GLASS), in the redshift range 1 < z < 6 Bradley et al 2014;Monna et al 2014) in the cluster field. There is general agreement that the mass distribution has a symmetric relaxed form with an obvious large-scale elongation .…”

“…This cluster has been studied previously in the context of gravitational lensing because of its status as one of the largest lenses in the Southern sky. It was chosen as a target for the CLASH program, which confirmed it as a valuable lens by virtue of its large magnification (Balestra et al 2013;Boone et al 2013;Gruen et al 2013;Bradley et al 2014;Johnson et al 2014;Monna et al 2014;Richard et al 2014;Umetsu et al 2015;Zitrin et al 2015). Recently, VLT spectroscopy has provided accurate redshifts for many of the previously known arclets Caminha et al (2015a).…”