Mauricio Carrasco

CLASH: three strongly lensed images of a candidate z ≈ 11 galaxy

We present a candidate for the most distant galaxy known to date with a photometric redshift of z = 10.7+0.6 –0.4 (95% confidence limits; with z < 9.5 galaxies of known types ruled out at 7.2σ). This J-dropout Lyman break galaxy, named MACS0647-JD, was discovered as part of the Cluster Lensing and Supernova survey with Hubble (CLASH). We observe three magnified images of this galaxy due to strong gravitational lensing by the galaxy cluster MACSJ0647.7+7015 at z = 0.591. The images are magnified by factors of ~80, 7, and 2, with the brighter two observed at ~26th magnitude AB (~0.15 μJy) in the WFC3/IR F160W filter (~1.4-1.7 μm) where they are detected at 12σ. All three images are also confidently detected at 6σ in F140W (~1.2-1.6 μm), dropping out of detection from 15 lower wavelength Hubble Space Telescope filters (~0.2-1.4 μm), and lacking bright detections in Spitzer/IRAC 3.6 μm and 4.5 μm imaging (~3.2-5.0 μm). We rule out a broad range of possible lower redshift interlopers, including some previously published as high-redshift candidates. Our high-redshift conclusion is more conservative than if we had neglected a Bayesian photometric redshift prior. Given CLASH observations of 17 high-mass clusters to date, our discoveries of MACS0647-JD at z ~ 10.8 and MACS1149-JD at z ~ 9.6 are consistent with a lensed luminosity function extrapolated from lower redshifts. This would suggest that low-luminosity galaxies could have reionized the universe. However, given the significant uncertainties based on only two galaxies, we cannot yet rule out the sharp drop-off in number counts at z 10 suggested by field searches.

A magnified young galaxy from about 500 million years after the Big Bang

Re-ionization of the intergalactic medium occurred in the early Universe at redshift z ≈ 6–11, following the formation of the first generation of stars. Those young galaxies (where the bulk of stars formed) at a cosmic age of less than about 500 million years (z ≲ 10) remain largely unexplored because they are at or beyond the sensitivity limits of existing large telescopes. Understanding the properties of these galaxies is critical to identifying the source of the radiation that re-ionized the intergalactic medium. Gravitational lensing by galaxy clusters allows the detection of high-redshift galaxies fainter than what otherwise could be found in the deepest images of the sky. Here we report multiband observations of the cluster MACS J1149+2223 that have revealed (with high probability) a gravitationally magnified galaxy from the early Universe, at a redshift of z = 9.6 ± 0.2 (that is, a cosmic age of 490 ± 15 million years, or 3.6 per cent of the age of the Universe). We estimate that it formed less than 200 million years after the Big Bang (at the 95 per cent confidence level), implying a formation redshift of ≲14. Given the small sky area that our observations cover, faint galaxies seem to be abundant at such a young cosmic age, suggesting that they may be the dominant source for the early re-ionization of the intergalactic medium.Johns Hopkins University, 3701 San Martin Drive, Baltimore , MD 21218, U.S.A. Space Telescope Science Institute Universität Heidelberg University of California, San Diego University of Science and Technology of China University College London Institute de Ciencies de l’Espai Instituto de Astrofı́sica de Andalucı́a Jet Propulsion Laboratory, California Institute of Techno logy Pontificia Universidad Católica de Chile National Optical Astronomical Observatory Universitas Sternwarte, München Leiden Observatory University of Basque Country

A census of star-forming galaxies in the z ∼ 9-10 universe based on hst+spitzer observations over 19 clash clusters: Three candidate z ∼ 9-10 galaxies and improved constraints on the star formation rate density at z

We utilise a two-color Lyman-Break selection criterion to search for z � 9-10 galaxies over the first 19 clusters in the CLASH program. Key to this search are deep observations over our clusters in five near-IR passbands to 1.6µm, allowing us good constraints on the position of the Lyman break to z � 10. A systematic search yields three z � 9-10 candidates in total above a 6� detection limit. While we have already reported the most robust of these candidates, MACS1149-JD, in a previous publication, two additional z � 9 candidates are also revealed in our expanded search. The new candidates have H160-band AB magnitudes of �26.2-26.9 and are located behind MACSJ1115.9+0129 and MACSJ1720.3+3536. The observed H160 Spitzer/IRAC colors for the sources are sufficiently blue to strongly favor redshifts of z � 9 for these sources. A careful assessment of various sources of contamination suggests .1 contaminants for our z � 9-10 selection. To determine the implications of these search results for the LF and SFR density at z � 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 � 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 � 8. This procedure takes advantage of the fact that the relative selection volumes available for the z � 8 and z � 9-10 selections behind lensing clusters are not greatly dependent on the details of the gravitational lensing models. We find that the normalization of the UV LF at z � 9 is just 0.22 +0.30 −0.15 × that at z � 8, �2 +31× lower than what we would infer extrapolating z � 4-8 LF results. These results therefore suggest a more rapid evolution in the UV LF at z > 8 than seen at lower redshifts (although the current evidence here is weak). Compared to similar evolutionary findings from the HUDF, our result is much more insensitive to large-scale structure uncertainties, given our many independent sightlines on the high-redshift universe. Subject headings: galaxies: evolution — galaxies: high-redshift

CLASH: The CONCENTRATION-MASS RELATION of GALAXY CLUSTERS

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 × 10^(15) M_⊙ h and 1.76 × 10^(15) M_⊙ h and the halo concentrations are distributed around c_(200c) ∼ 3.7 with a 1σ 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.

Hubble Space Telescope Combined Strong and Weak Lensing Analysis of the CLASH Sample: Mass and Magnification Models and Systematic Uncertainties

We present results from a comprehensive lensing analysis in HST data, of the complete CLASH cluster sample. We identify new multiple-images previously undiscovered allowing improved or first constraints on the cluster inner mass distributions and profiles. We combine these strong-lensing constraints with weak-lensing shape measurements within the HST FOV to jointly constrain the mass distributions. The analysis is performed in two different common parameterizations (one adopts light-traces-mass for both galaxies and dark matter while the other adopts an analytical, elliptical NFW form for the dark matter), to provide a better assessment of the underlying systematics - which is most important for deep, cluster-lensing surveys, especially when studying magnified high-redshift objects. We find that the typical (median), relative systematic differences throughout the central FOV are

CLASH: Precise new constraints on the mass profile of the galaxy cluster A2261

\sim40\%

The ALMA Frontier Fields Survey: I. 1.1 mm continuum detections in Abell 2744, MACS J0416.1-2403 and MACS J1149.5+2223

in the (dimensionless) mass density,

The ALMA Frontier Fields Survey. IV. Lensing-corrected 1.1 mm number counts in Abell 2744, MACSJ0416.1-2403 and MACSJ1149.5+2223

\kappa

VLT/MAGELLAN SPECTROSCOPY of 29 STRONG LENSING SELECTED GALAXY CLUSTERS

, and

The ALMA Frontier Fields Survey: III. 1.1 mm emission line identifications in Abell 2744, MACSJ 0416.1-2403, MACSJ 1149.5+2223, Abell 370, and Abell S1063

\sim20\%