The deflection angles of lensed sources increase with their distance behind a given lens. We utilize this geometric effect to corroborate the z(phot) similar or equal to 9.8 photometric redshift estimate of a faint near-IR dropout, triply imaged by the massive galaxy cluster A2744 in deep Hubble Frontier Fields images. The multiple images of this source follow the same symmetry as other nearby sets of multiple images that bracket the critical curves and have well-defined redshifts (up to z(spec) similar or equal to 3.6), but with larger deflection angles, indicating that this source must lie at a higher redshift. Similarly, our different parametric and non-parametric lens models all require this object be at z greater than or similar to 4, with at least 95% confidence, thoroughly excluding the possibility of lower-redshift interlopers. To study the properties of this source, we correct the two brighter images for their magnifications, leading to a star formation rate of similar to 0.3M(circle dot) yr(-1), a stellar mass of similar to 4 x 10(7) M-circle dot, and an age of less than or similar to 220 Myr (95% confidence). The intrinsic apparent magnitude is 29.9 AB (F160W), and the rest-frame UV (similar to 1500 angstrom) absolute magnitude is M-UV,M-AB = -17.6. This corresponds to similar to 0.1L(z=8)(*) (similar to 0.2 L-z=10(*), adopting dM(*)/dz similar to 0.45), making this candidate one of the least luminous galaxies discovered at z similar to 10.

Aims. We aim constrain the assembly history of clusters by studying the intracluster light (ICL) properties, estimating its contribution to the fraction of baryons in stars, f(*), and understanding possible systematics or bias using different ICL detection techniques.

We utilize a two-color Lyman-break selection criterion to search for z similar to 9-10 galaxies over the first 19 clusters in the CLASH program. A systematic search yields three z similar to 9-10 candidates. While we have already reported the most robust of these candidates, MACS1149-JD, two additional z similar to 9 candidates are also found and have H-160- band magnitudes of similar to 26.2-26.9. A careful assessment of various sources of contamination suggests less than or similar to 1 contaminants for our z similar to 9-10 selection. To determine the implications of these search results for the luminosity function (LF) and star formation rate density at z similar to 9, we introduce a new differential approach to deriving these quantities in lensing fields. Our procedure is to derive the evolution by comparing the number of z similar to 9-10 galaxy candidates found in CLASH with the number of galaxies in a slightly lower-redshift sample (after correcting for the differences in selection volumes), here taken to be z similar to 8. This procedure takes advantage of the fact that the relative volumes available for the z similar to 8 and z similar to 9-10 selections behind lensing clusters are not greatly dependent on the details of the lensing models. We find that the normalization of the UV LF at z similar to 9 is just 0.28(-0.20)(+0.39) x that at z similar to 8, which is similar to 1.4(-0.8)(+3.0) x lower than extrapolating z similar to 4-8 LF results. While consistent with the evolution in the UV LF seen at z similar to 4-8, these results marginally favor a more rapid evolution at z > 8. Compared to similar evolutionary findings from the HUDF, our result is less insensitive to large-scale structure uncertainties, given our many independent sightlines on the high-redshift universe.

We report the discovery of 24 Lyman-break candidates at 7 less than or similar to z less than or similar to 10.5, in the Hubble Frontier Fields (HFF) imaging data of A2744 (z = 0.308), plus Spitzer/IRAC data and archival ACS data. The sample includes a triple image system with a photometric redshift of z similar or equal to 7.4. This high redshift is geometrically confirmed by our lens model corresponding to deflection angles that are 12% larger than the lower-redshift systems used to calibrate the lens model at z = 2.019. The majority of our high-redshift candidates are not expected to be multiply lensed given their locations in the image plane and the brightness of foreground galaxies, but are magnified by factors of similar to 1.3-15, so that we are seeing further down the luminosity function than comparable deep-field imaging. It is apparent that the redshift distribution of these sources does not smoothly extend over the full redshift range accessible at z < 12, but appears to break above z = 9. Nine candidates are clustered within a small region of 20 '' across, representing a potentially unprecedented concentration. Given the poor statistics, however, we must await similar constraints from the additional HFF clusters to properly examine this trend. The physical properties of our candidates are examined using the range of lens models developed for the HFF program by various groups including our own, for a better estimate of underlying systematics. Our spectral-energy-distribution fits for the brightest objects suggest stellar masses of similar or equal to 10(9) M-circle dot, star formation rates of similar or equal to 4 M-circle dot yr(-1), and a typical formation redshift of z less than or similar to 19.

We present an analysis of the MUSIC-2 N-body/hydrodynamical simulations aimed at estimating the expected concentration-mass relation for the CLASH (Cluster Lensing and Supernova Survey with Hubble) cluster sample. We study nearly 1,400 halos simulated at high spatial and mass resolution. We study the shape of both their density and surface-density profiles and fit them with a variety of radial functions, including the Navarro-Frenk-White (NFW), the generalized NFW, and the Einasto density profiles. We derive concentrations and masses from these fits. We produce simulated Chandra observations of the halos, and we use them to identify objects resembling the X-ray morphologies and masses of the clusters in the CLASH X-ray-selected sample. We also derive a concentration-mass relation for strong-lensing clusters. We find that the sample of simulated halos that resembles the X-ray morphology of the CLASH clusters is composed mainly of relaxed halos, but it also contains a significant fraction of unrelaxed systems. For such a heterogeneous sample we measure an average two-dimensional concentration that is similar to 11% higher than is found for the full sample of simulated halos. After accounting for projection and selection effects, the average NFW concentrations of CLASH clusters are expected to be intermediate between those predicted in three dimensions for relaxed and super-relaxed halos. Matching the simulations to the individual CLASH clusters on the basis of the X-ray morphology, we expect that the NFW concentrations recovered from the lensing analysis of the CLASH clusters are in the range [3-6], with an average value of 3.87 and a standard deviation of 0.61.

We present results on the stellar population properties of massive galaxies at z = 0.7 based on deep, medium-resolution IMACS spectra for a sample of similar to 70 galaxies in the ECDFS with M-* > 10(10) M-circle dot. The age-mass and stellar metallicity-mass relations for the population as a whole have a similar shape as the local relations over the probed mass range, but offset to ages younger by similar to 4 Gyr and metallicities lower by similar to 0.13 dex. Quiescent galaxies alone have stellar ages and metallicities consistent with passive evolution onto the local quiescent galaxies relations. The evolution in metallicity is driven by star-forming galaxies. However a significant fraction of massive star-forming galaxies have metallicities comparable to those of local quiescent galaxies. If quenched at z < 0.7 they can provide the necessary population to reproduce the scatter in age and metallicity of local quiescent galaxies.

We utilize the Cluster Lensing And Supernova survey with Hubble observations of 25 clusters to search for extreme emission-line galaxies (EELGs). The selections are carried out in two central bands: F105W (Y-105) and F125W (J(125)), as the flux of the central bands could be enhanced by the presence of [O (III)] lambda lambda 4959, 5007 at redshifts of similar to 0.93-1.14 and 1.57-1.79, respectively. The multiband observations help to constrain the equivalent widths (EWs) of emission lines. Thanks to cluster lensing, we are able to identify 52 candidates down to an intrinsic limiting magnitude of 28.5 and to a rest-frame [O (III)] lambda lambda 4959, 5007 EW of similar or equal to 3700 angstrom. Our samples include a number of EELGs at lower luminosities that are missed in other surveys, and the extremely high EW can only be found in such faint galaxies. These EELGs can mimic a dropout feature similar to that of high-redshift galaxies and contaminate the color-color selection of high-redshift galaxies when the signal-to-noise ratio is limited or the band coverage is incomplete.

We report on our first set of spectroscopic Hubble Space Telescope observations of the z approximate to 11 candidate galaxy, which is strongly lensed by the MACSJ 0647.7+7015 galaxy cluster. The three lensed images are faint and we show that these early slitless grism observations are of sufficient depth to investigate whether this high-redshift candidate, identified by its strong photometric break at approximate to 1.5 mu m, could possibly be an emission line galaxy at a much lower redshift. While such an interloper would imply the existence of a rather peculiar object, we show here that such strong emission lines would clearly have been detected. Comparing realistic, two-dimensional simulations to these new observations, we would expect the necessary emission lines to be detected at >5 sigma, though we see no evidence for such lines in the dispersed data of any of the three lensed images. We therefore exclude that this object could be a low-redshift emission line interloper, which significantly increases the likelihood of this candidate being a bona fide z approximate to 11 galaxy.

Context. The study of the galaxy stellar mass function (SMF) in relation to the galaxy environment and the stellar mass density profile, rho(star)(r), is a powerful tool to constrain models of galaxy evolution.

We present a new determination of the concentration-mass (c-M) relation for galaxy clusters based on our comprehensive lensing analysis of 19 X-ray selected galaxy clusters from the Cluster Lensing and Supernova Survey with Hubble (CLASH). Our sample spans a redshift range between 0.19 and 0.89. We combine weak-lensing constraints from the Hubble Space Telescope (HST) and from ground-based wide-field data with strong lensing constraints from HST. The results are reconstructions of the surface-mass density for all CLASH clusters on multi-scale grids. Our derivation of Navarro-Frenk-White parameters yields virial masses between 0.53 x 10(15) M-circle dot/h and 1.76 x 10(15) M-circle dot/h and the halo concentrations are distributed around c(200c) similar to 3.7 with a 1 sigma significant negative slope with cluster mass. We find an excellent 4% agreement in the median ratio of our measured concentrations for each cluster and the respective expectation from numerical simulations after accounting for the CLASH selection function based on X-ray morphology. The simulations are analyzed in two dimensions to account for possible biases in the lensing reconstructions due to projection effects. The theoretical c-M relation from our X-ray selected set of simulated clusters and the c-M relation derived directly from the CLASH data agree at the 90% confidence level.