K. H. Huang

EXTREME EMISSION-LINE GALAXIES IN CANDELS: BROADBAND-SELECTED, STARBURSTING DWARF GALAXIES AT z > 1

We identify an abundant population of extreme emission-line galaxies (EELGs) at redshift z ~ 1.7 in the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey imaging from Hubble Space Telescope/Wide Field Camera 3 (HST/WFC3). Sixty-nine EELG candidates are selected by the large contribution of exceptionally bright emission lines to their near-infrared broadband magnitudes. Supported by spectroscopic confirmation of strong [O III] emission lines—with rest-frame equivalent widths ~1000 A—in the four candidates that have HST/WFC3 grism observations, we conclude that these objects are galaxies with ~108 M ☉ in stellar mass, undergoing an enormous starburst phase with of only ~15xa0Myr. These bursts may cause outflows that are strong enough to produce cored dark matter profiles in low-mass galaxies. The individual star formation rates and the comoving number density (3.7 × 10–4 Mpc–3) can produce in ~4xa0Gyr much of the stellar mass density that is presently contained in 108-109 M ☉ dwarf galaxies. Therefore, our observations provide a strong indication that many or even most of the stars in present-day dwarf galaxies formed in strong, short-lived bursts, mostly at z > 1.

The grism lens-amplified survey from space (glass). i. survey overview and first data release

We give an overview of the Grism Lens Amplified Survey from Space (GLASS), a large Hubble Space Telescope program aimed at obtaining grism spectroscopy of the fields of ten massive clusters of galaxies at redshift z=0.308-0.686, including the Hubble Frontier Fields (HFF). The Wide Field Camera 3 yields near infrared spectra of the cluster cores, covering the wavelength range 0.81-1.69mum through grisms G102 and G141, while the Advanced Camera for Surveys in parallel mode provides G800L spectra of the infall regions of the clusters. The WFC3 spectra are taken at two almost orthogonal position angles in order to minimize the effects of confusion. After summarizing the scientific drivers of GLASS, we describe the sample selection as well as the observing strategy and data processing pipeline. We then utilize MACSJ0717.5+3745, a HFF cluster and the first one observed by GLASS, to illustrate the data quality and the high-level data products. Each spectrum brighter than H_AB=23 is visually inspected by at least two co-authors and a redshift is measured when sufficient information is present in the spectra. Furthermore, we conducted a thorough search for emission lines through all the GLASS WFC3 spectra with the aim of measuring redshifts for sources with continuum fainter than H_AB=23. We provide a catalog of 139 emission-line based spectroscopic redshifts for extragalactic sources, including three new redshifts of multiple image systems (one probable, two tentative). In addition to the data itself we also release software tools that are helpful to navigate the data.

Deconstructing the galaxy stellar mass function with UKIDSS and CANDELS: the impact of colour, structure and environment

We combine photometry from the Ultra Deep Survey (UDS), Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) UDS and CANDELS the Great Observatories Origins Deep Survey-South (GOODS-S) surveys to construct the galaxy stellar mass function probing both the low-and high-mass end accurately in the redshift range 0.3 26.0), affording us robust measures of structural parameters. We construct stellar mass functions for the entire sample as parametrized by the Schechter function, and find that there is a decline in the values of phi and of alpha with higher redshifts, and a nearly constant M* up to z similar to 3. We divide the galaxy stellar mass function by colour, structure, and environment and explore the links between environmental overdensity, morphology, and the quenching of star formation. We find that a double Schechter function describes galaxies with high Sersic index (n > 2.5), similar to galaxies which are red or passive. The low-mass end of the n > 2.5 stellar mass function is dominated by blue galaxies, whereas the high-mass end is dominated by red galaxies. This shows that there is a possible link between morphological evolution and star formation quenching in high mass galaxies, which is not seen in lower mass systems. This in turn suggests that there are strong mass-dependent quenching mechanisms. In addition, we find that the number density of high-mass systems is elevated in dense environments, suggesting that an environmental process is building up massive galaxies quicker in over densities than in lower densities.

THE GRISM LENS-AMPLIFIED SURVEY FROM SPACE (GLASS). III. A CENSUS OF Lyα EMISSION AT z ≳ 7 FROM HST SPECTROSCOPY

Draft version November 16, 2015 Preprint typeset using L A TEX style emulateapj v. 5/2/11 THE GRISM LENS-AMPLIFIED SURVEY FROM SPACE (GLASS). III. A CENSUS OF Lyα EMISSION AT z & 7 FROM HST SPECTROSCOPY ˇ 4 , B. Vulcani 5 , K.-H., Huang 4 , A. Hoag 4 , M. Maseda 6 L. Guaita 7 K. B. Schmidt 1,2 , T. Treu 3 , M. Brada c L. Pentericci 7 , G. B. Brammer 8 , M. Dijkstra 9 , A. Dressler 10 A. Fontana 7 , A. L. Henry 11 , T. A. Jones 1 , C. Mason 1 , M. Trenti 12 , X. Wang 1 , 1 Department of Physics, University of California, Santa Barbara, CA, 93106-9530, USA Leibniz-Institut f¨ ur Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany 3 Department of Physics and Astronomy, UCLA, Los Angeles, CA, 90095-1547, USA 4 Department of Physics, University of California, Davis, CA, 95616, USA Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, the University of Tokyo, Kashiwa, 277-8582, Japan 6 Max-Planck-Institut f¨ ur Astronomie, K¨ onigstuhl 17, D-69117 Heidelberg, Germany 7 INAF - Osservatorio Astronomico di Roma Via Frascati 33 - 00040 Monte Porzio Catone, I 8 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD, 21218, USA 9 Institute of Theoretical Astrophysics, University of Oslo, Postboks 1029, 0858 Oslo, Norway 10 The Observatories of the Carnegie Institution for Science, 813 Santa Barbara St., Pasadena, CA 91101, USA 11 Astrophysics Science Division, Goddard Space Flight Center, Code 665, Greenbelt, MD 20771 and 12 School of Physics, The University of Melbourne, VIC, 3010 Australia Draft version November 16, 2015 arXiv:1511.04205v1 [astro-ph.GA] 13 Nov 2015 ABSTRACT We present a census of Lyα emission at z & 7 utilizing deep near infrared HST grism spectroscopy from the first six completed clusters of the Grism Lens-Amplified Survey from Space (GLASS). In 24/159 photometrically selected galaxies we detect emission lines consistent with Lyα in the GLASS spectra. Based on the distribution of signal-to-noise ratios and on simulations we expect the com- pleteness and the purity of the sample to be 40-100% and 60-90%, respectively. For the objects without detected emission lines we show that the observed (not corrected for lensing magnification) 1σ flux limits reaches 5 × 10 −18 erg/s/cm 2 per position angle over the full wavelength range of GLASS (0.8–1.7µm). Based on the conditional probability of Lyα emission measured from the ground at z ∼ 7 we would have expected 12-18 Lyα emitters. This is consistent with the number of detections, within the uncertainties, confirming the drop in Lyα emission with respect to z ∼ 6. Deeper follow-up spectroscopy, here exemplified by Keck spectroscopy, is necessary to improve our estimates of com- pleteness and purity, and to confirm individual candidates as true Lyα emitters. These candidates include a promising source at z = 8.1. The spatial extent of Lyα in a deep stack of the most convincing Lyα emitters with hzi = 7.2 is consistent with that of the rest-frame UV continuum. Extended Lyα emission, if present, has a surface brightness below our detection limit, consistent with the properties of lower redshift comparison samples. From the stack we estimate upper limits on rest-frame UV emission line ratios and find f CIV /f Lyα . 0.32 and f CIII] /f Lyα . 0.23 in good agreement with other values published in the literature. Subject headings: galaxies: high-redshift – techniques: spectroscopic – methods: data analysis 1. INTRODUCTION With the deployment of the wide field camera 3 (WFC3) on the Hubble Space Telescope (HST ) in 2009, the samples of galaxies at the epoch of reionization, the phase-transition from a completely neutral inter-galactic medium (IGM) to a fully ionized IGM at z & 6, have grown dramatically. One of the main results of the WFC3 imaging campaigns has been the accurate deter- mination of the luminosity function of star forming high- redshift (based on their photometry) Lyman break galax- ies (e.g. Bouwens et al. 2015b; Finkelstein et al. 2015b). The UV luminosity functions of Lyman break galaxies have provided key constraints on the physics of reioniza- tion (e.g. Robertson et al. 2013; Schmidt et al. 2014a; Duffy et al. 2014). For example, it is clear that the pop- ulation of galaxies that has been detected so far cannot produce enough hard photons to keep the universe ion- ized. However, the luminosity function is found to have kbschmidt@aip.de a steep faint end slope (approximately φ ∝ L −2 ). Thus, faint galaxies could in principle provide enough ionizing photons (Bouwens et al. 2015a; Robertson et al. 2015; Barone-Nugent et al. 2015; Dressler et al. 2015). even though a contribution from AGN might end up being necessary (Madau & Haardt 2015; Giallongo et al. 2015). Also ground based spectroscopic follow-up of photo- metrically selected high-redshift candidates has been an important part of these studies and has provided addi- tional clues about the reionization epoch. Remarkably, only a handful of sources have been confirmed above red- shift 7 (Vanzella et al. 2011; Schenker et al. 2012, 2014; Ono et al. 2012; Finkelstein et al. 2013; Oesch et al. 2015; Roberts-Borsani et al. 2015; Zitrin et al. 2015b). The low probability of detecting Lyα in Lyman break galaxies, could be interpreted as the result of an increased optical depth in the IGM due to a significant fraction of neutral hydrogen. Thus the decline in detected Lyα is poten- tially a “smoking gun” of reionization (Fontana et al. 2010). The conditional probability of Lyα emission for

THE GRISM LENS-AMPLIFIED SURVEY FROM SPACE (GLASS). IV. MASS RECONSTRUCTION OF THE LENSING CLUSTER ABELL 2744 FROM FRONTIER FIELD IMAGING AND GLASS SPECTROSCOPY

We present a strong and weak lensing reconstruction of the massive cluster Abell 2744, the first cluster for which deep Hubble Frontier Field (HFF) images and spectroscopy from the Grism Lens-Amplified Survey from Space (GLASS) are available. By performing a targeted search for emission lines in multiply imaged sources using the GLASS spectra, we obtain 5 high-confidence spectroscopic redshifts and 2 tentative ones. We confirm 1 strongly lensed system by detecting the same emission lines in all 3 multiple images. We also search for additional line emitters blindly and use the full GLASS spectroscopic catalog to test reliability of photometric redshifts for faint line emitters. We see a reasonable agreement between our photometric and spectroscopic redshift measurements, when including nebular emission in photometric redshift estimations. We introduce a stringent procedure to identify only secure multiple image sets based on colors, morphology, and spectroscopy. By combining 7 multiple image systems with secure spectroscopic redshifts (at 5 distinct redshift planes) with 18 multiple image systems with secure photometric redshifts, we reconstruct the gravitational potential of the cluster pixellated on an adaptive grid, using a total of 72 images. The resulting mass map is compared with a stellar mass map obtained from the deep Spitzer Frontier Fields data to study the relative distribution of stars and dark matter in the cluster. We find that the stellar to total mass ratio varies substantially across the cluster field, suggesting that stars do not trace exactly the total mass in this interacting system. The maps of convergence, shear, and magnification are made available in the standard HFF format.

CANDELS MULTI-WAVELENGTH CATALOGS: SOURCE IDENTIFICATION AND PHOTOMETRY IN THE CANDELS COSMOS SURVEY FIELD

We present a multi-wavelength photometric catalog in the COSMOS field as part of the observations by the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey. The catalog is based on Hubble Space Telescope Wide Field Camera 3 (HST/WFC3) and Advanced Camera for Surveys observations of the COSMOS field (centered at R.A.: 10^h00^m28^s, Decl.:+02^o12^21^). The final catalog has 38671 sources with photometric data in 42 bands from UV to the infrared (~ 0.3-8 µm). This includes broadband photometry from HST, CFHT, Subaru, the Visible and Infrared Survey Telescope for Astronomy, and Spitzer Space Telescope in the visible, near-infrared, and infrared bands along with intermediate- and narrowband photometry from Subaru and medium-band data from Mayall NEWFIRM. Source detection was conducted in the WFC3 F160W band (at 1.6 μm) and photometry is generated using the Template FITting algorithm. We further present a catalog of the physical properties of sources as identified in the HST F160W band and measured from the multi-band photometry by fitting the observed spectral energy distributions of sources against templates.

Measuring the stellar masses of z ∼ 7 galaxies with the spitzer ultrafaint survey program (Surfs up)

We present Spitzer/IRAC observations of nine z-band dropouts highly magnified (2 ≲ μ ≲ 12) by the Bullet Cluster. We combine archival imaging with our Exploratory program (SURFS UP), which results in a total integration time of ∼30 hr per Infrared Array Camera (IRAC) band. We detect (≳ 3σ) in both IRAC bands the brightest of these high-redshift galaxies, with [3.6] = 23.80 ± 0.28 mag, [4.5] = 23.78 ± 0.25 mag, and (H – [3.6]) = 1.17 ± 0.32 mag. The remaining eight galaxies are undetected to [3.6] ∼ 26.4 mag and [4.5] ∼ 26.0 mag with stellar masses of ∼5 × 10{sup 7} M {sub ☉}. The detected galaxy has an estimated magnification of μ = 12 ± 4, which implies this galaxy has an ultraviolet luminosity of L{sub 1500}∼0.3 L{sub z=7}{sup ∗}—the lowest-luminosity individual source detected in IRAC at z ≳ 7. By modeling the broadband photometry, we estimate the galaxy has an intrinsic star formation rate (SFR) of SFR ∼ 1.3 M {sub ☉} yr{sup –1} and stellar mass of M ∼ 2.0 × 10{sup 9} M {sub ☉}, which gives a specific star formation rate of sSFR ∼ 0.7 Gyr{sup –1}. If this galaxy had sustained this SFR since z ∼morexa0» 20, it could have formed the observed stellar mass (to within a factor of ∼2). We also discuss alternate star formation histories and argue that the exponentially increasing model is unlikely. Finally, based on the intrinsic SFR, we estimate that this galaxy has a likely [C II] flux of (f {sub [C} {sub II]}) = 1.6 mJy.«xa0less

RCS2 J232727.6-020437: AN EFFICIENT COSMIC TELESCOPE at z = 0.6986

Here, we present a detailed gravitational lens model of the galaxy cluster RCS2 J232727.6-020437. Due to cosmological dimming of cluster members and ICL, its high redshift (z=0.6986) makes it ideal for studying background galaxies. Using new ACS and WFC3/IR HST data, we identify 16 multiple images. From MOSFIRE follow up, we identify a strong emission line in the spectrum of one multiple image, likely confirming the redshift of that system to z=2.083. With a highly magnified (μ ≳ 2) source plane area of ~ 0.7 arcmin2 at z = 7, RCS2 J232727.6-020437 has a lensing efficiency comparable to the Hubble Frontier Fields clusters. We discover four highly magnified z ~ 7 candidate Lyman-break galaxies behind the cluster, one of which may be multiply-imaged. Correcting for magnification, we find that all four galaxies are fainter than 0.5L*. One candidate is detected at >10σ in both Spitzer/IRAC [3.6] and [4.5] channels. A spectroscopic follow-up with MOSFIRE does not result in the detection of the Lyman-alpha emission line from any of the four candidates. From the MOSFIRE spectra we place median upper limits on the Lyman-alpha flux of 5 – 14 × 10–19 ergs–1cm–2 (5σ).

HST Grism Observations of a Gravitationally Lensed Redshift 9.5 Galaxy

© 2018. The American Astronomical Society. All rights reserved. We present deep spectroscopic observations of a Lyman break galaxy (LBG) candidate (hereafter MACS1149-JD) at z ∼ 9.5 with the Hubble Space Telescope (HST) WFC3/IR grisms. The grism observations were taken at four distinct position angles, totaling 34 orbits with the G141 grism, although only 19 of the orbits are relatively uncontaminated along the trace of MACS1149-JD. We fit a three-parameter (z, F160W mag, and Lyα equivalent width [EW]) LBG template to the three least contaminated grism position angles using a Markov chain Monte Carlo approach. The grism data alone are best fit with a redshift of (68% confidence), in good agreement with our photometric estimate of (68% confidence). Our analysis rules out Lyα emission from MACS1149-JD above a 3σ EW of 21 A, consistent with a highly neutral IGM. We explore a scenario where the red Spitzer/IRAC [3.6]-[4.5] color of the galaxy previously pointed out in the literature is due to strong rest-frame optical emission lines from a very young stellar population rather than a 4000 A break. We find that while this can provide an explanation for the observed IRAC color, it requires a lower redshift (z ≲ 9.1), which is less preferred by the HST imaging data. The grism data are consistent with both scenarios, indicating that the red IRAC color can still be explained by a 4000 A break, characteristic of a relatively evolved stellar population. In this interpretation, the photometry indicates that a Myr stellar population is already present in this galaxy only ∼500 Myr after the big bang.

The Grism Lens-amplified Survey from Space (GLASS). XII. Spatially Resolved Galaxy Star Formation Histories and True Evolutionary Paths at z > 1

Modern data empower observers to describe galaxies as the spatially and biographically complex objects they are. We illustrate this through case studies of four,