We show that a model consisting of individual, log-normal star formation histories for a volume-limited sample of z approximate to 0 galaxies reproduces the evolution of the total and quiescent stellar mass functions at z less than or similar to 2.5 and stellar massesM(*) >= 10(10) M-circle dot. This model has previously been shown to reproduce the star formation rate/stellar mass relation (SFR-M-*) over the same interval, is fully consistent with the observed evolution of the cosmic SFR density at z <= 8, and entails no explicit "quenching" prescription. We interpret these results/features in the context of other models demonstrating a similar ability to reproduce the evolution of (1) the cosmic SFR density, (2) the total/quiescent stellar mass functions, and (3) the SFR-M-* relation, proposing that the key difference between modeling approaches is the extent to which they stress/address diversity in the (star-forming) galaxy population. Finally, we suggest that observations revealing the timescale associated with dispersion in SFR(M-*) will help establish which models are the most relevant to galaxy evolution.

We present spatially resolved gas-phase metallicity for a system of three galaxies at z = 1.85 detected in the Grism Lens-Amplified Survey from Space (GLASS). The combination of Hubble Space Telescope (HST's) diffraction limit and strong gravitational lensing by the cluster MACS J0717+3745 results in a spatial resolution of similar or equal to 200-300 pc, enabling good spatial sampling despite the intrinsically small galaxy sizes. The galaxies in this system are separated by similar to 50-200 kpc in projection and are likely in an early stage of interaction, evidenced by relatively high specific star formation rates. Their gas-phase metallicities are consistent with larger samples at similar redshift, star formation rate (SFR), and stellar mass. We obtain a precise measurement of the metallicity gradient for one galaxy and find a shallow slope compared to isolated galaxies at high redshift, consistent with a flattening of the gradient due to gravitational interaction. An alternative explanation for the shallow metallicity gradient and elevated SFR is rapid recycling of metal-enriched gas, but we find no evidence for enhanced gas-phase metallicities which should result from this effect. Notably, the measured stellar masses log M*/M-circle dot = 7.2-9.1 probe to an order of magnitude below previous mass-metallicity studies at this redshift. The lowest mass galaxy has properties similar to those expected for Fornax at this redshift, indicating that GLASS is able to directly study the progenitors of local group dwarf galaxies on spatially resolved scales. Larger samples from the full GLASS survey will be ideal for studying the effects of feedback, and the time evolution of metallicity gradients. These initial results demonstrate the utility of HST spectroscopy combined with gravitational lensing for characterizing resolved physical properties of galaxies at high redshift.

Context. Cluster galaxies are the ideal sites to look at when studying the influence of the environment on the various aspects of the evolution of galaxies, such as the changes in their stellar content and morphological transformations. In the framework of wings, the WIde-field Nearby Galaxy-cluster Survey, we have obtained optical spectra for similar to 6000 galaxies selected in fields centred on 48 local (0.04 < z < 0.07) X-ray selected clusters to tackle these issues.

We present the morphology-density and morphology-radius relations (T-Sigma and T-R, respectively) obtained from the WIde-field Nearby Galaxy-cluster Survey (WINGS) data base of galaxies in nearby clusters. Aiming to achieve the best statistics, we exploit the whole sample of galaxies brighter than M-V = -19.5 (5504 objects), stacking up the 76 clusters of the WINGS survey altogether. Using this global cluster sample, we find that the T-Sigma relation holds only in the inner cluster regions (R < 1/3 R-200), while the T-R relation keeps almost unchanged over the whole range of local density. A couple of tests and two sets of numerical simulations support the robustness of these results against the effects of the limited cluster area coverage of the WINGS imaging. The above mentioned results hold for all cluster masses (X-ray luminosity and velocity dispersion) and all galaxy stellar masses (M-*). The strength of the T-Sigma relation (where present) increases with increasing M-*, while this effect is not found for the T-R relation. Noticeably, the absence/presence of subclustering determines the presence/absence of the T-Sigma relation outside the inner cluster regions, leading us to the general conclusion that the link between morphology and local density is preserved just in dynamically evolved regions. We hypothesize that some mechanism of morphological broadening/redistribution operates in the intermediate/outer regions of substructured ('non-relaxed') clusters, producing a strong weakening of the T-Sigma relation.

Upcoming space-based surveys such as Euclid and WFIRST-AFTA plan to measure baryonic acoustic oscillations in order to study dark energy. These surveys will use IR slitless grism spectroscopy to measure redshifts of a large number of galaxies over a significant redshift range. In this paper, we use the Wide Field Camera 3 Infrared Spectroscopic Parallel Survey (WISP) to estimate the expected number of H alpha emitters observable by these future surveys. WISP is an ongoing Hubble Space Telescope slitless spectroscopic survey, covering the 0.8-1.65 mu m wavelength range and allowing the detection of H alpha emitters up to z similar to 1.5 and [O III] emitters to z similar to 2.3. We derive the H alpha-[O III] bivariate line luminosity function (LLF) for WISP galaxies at z similar to 1 using a maximum likelihood estimator that properly accounts for uncertainties in line luminosity measurements and we demonstrate how it can be used to derive the H alpha luminosity function by exclusively fitting [O III] data. Using the z similar to 2 [O III] LLF and assuming that the relation between H alpha and [O III] luminosity does not change significantly over the redshift range, we predict the H alpha number counts at z similar to 2-the upper end of the redshift range of interest for future surveys. For the redshift range 0.7 < z < 2, we expect similar to 3000 galaxies deg(-2) for a flux limit of 3 x 10(-16) erg s(-1) cm(-2) (the proposed depth of the Euclid galaxy redshift survey) and similar to 20,000 galaxies deg(-2) for a flux limit of similar to 10(-16) erg s(-1) cm(-2) (the baseline depth of the WFIRST galaxy redshift survey).

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 10 massive clusters of galaxies at redshift z = 0.308-0.686, including the Hubble Frontier Fields (HFF). The Wide Field Camera 3 (WFC3) yields nearinfrared spectra of the cluster cores covering the wavelength range 0.81-1.69 mu m 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 MACS J0717.5+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 of 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.

We present a census of Ly alpha emission at z greater than or similar to 7, utilizing deep near-infrared Hubble Space Telescope 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 Ly alpha in the GLASS spectra. Based on the distribution of signal-to-noise ratios and on simulations, we expect the completeness 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) 1 sigma flux limits reach 5 x 10(-18) erg s(-1) cm(-2) per position angle over the full wavelength range of GLASS (0.8-1.7 mu m). Based on the conditional probability of Ly alpha emission measured from the ground at z similar to 7, we would have expected 12-18 Ly alpha emitters. This is consistent with the number of detections, within the uncertainties, confirming the drop in Ly alpha emission with respect to z similar to 6. Deeper follow-up spectroscopy, here exemplified by Keck spectroscopy, is necessary to improve our estimates of completeness and purity. and to confirm individual candidates as true Ly alpha emitters. These candidates include a promising source at z = 8.1. The spatial extent of Ly alpha in a deep stack of the most convincing Ly alpha emitters with < z > = 7.2 is consistent with that of the rest-frame UV continuum. Extended Ly alpha 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(C IV)/f(Ly alpha) less than or similar to 0.32 and f(C III])/f(Ly alpha) less than or similar to 0.23, in good agreement with other values published in the literature.

We present the first study of the spatial distribution of star formation in z similar to 0.5 cluster galaxies. The analysis is based on data taken with the Wide Field Camera 3 as part of the Grism Lens-Amplified Survey from Space (GLASS). We illustrate the methodology by focusing on two clusters (MACS 0717.5+3745 and MACS 1423.8 + 2404) with different morphologies (one relaxed and one merging) and use foreground and background galaxies as a field control sample. The cluster+field sample consists of 42 galaxies with stellar masses in the range 10(8)-10(11) M-circle dot and star formation rates in the range 1-20 M-circle dot yr(-1). Both in clusters and in the field, H alpha is more extended than the rest-frame UV continuum in 60% of the cases, consistent with diffuse star formation and inside-out growth. In similar to 20% of the cases, the H alpha emission appears more extended in cluster galaxies than in the field, pointing perhaps to ionized gas being stripped and/or star formation being enhanced at large radii. The peak of the H alpha emission and that of the continuum are offset by less than 1 kpc. We investigate trends with the hot gas density as traced by the X-ray emission, and with the surface mass density as inferred from gravitational lens models, and find no conclusive results. The diversity of morphologies and sizes observed in H alpha illustrates the complexity of the environmental processes that regulate star formation. Upcoming analysis of the full GLASS data set will increase our sample size by almost an order of magnitude, verifying and strengthening the inference from this initial data set.

WINGS is a wide-field multi-wavelength survey of 76 X-ray selected clusters at low redshift. The WINGS database has been used for a variety of cluster and cluster galaxy studies, investigating galaxy star formation, morphologies, structure, stellar mass functions and other properties. We present the recent wider-field extension of WINGS, OMEGAWINGS, conducted with OmegaCAM@VST and AAOmega@AAT. We show two of our latest results regarding jellyfish galaxies. I and galaxy sizes. OMEGAWINGS has allowed the first systematic search of galaxies with signs of ongoing ram pressure stripping (jellyfishes), yielding a catalog of similar to 240 galaxies in 41 clusters. We discuss the first results obtained from this sample and the prospects for integral field data. Finally, we summarize our results regarding the discovery of compact massive galaxies at low redshift, their properties, dependence on environment and the implications for the evolution of galaxy sizes from high-to low-z.

Exploiting the slitless spectroscopy taken as part of the Grism Lens-Amplified Survey from Space (GLASS), we present an extended analysis of the spatial distribution of star formation in 76 galaxies in 10 clusters at 0.3 < z < 0.7. We use 85 foreground and background galaxies in the same redshift range as a field sample. The samples are well matched in stellar mass (10(8)-10(11) M-circle dot) and star formation rate (0.550 M-circle dot yr(-1)). We visually classify galaxies in terms of broad band morphology, Ha morphology, and likely physical process acting on the galaxy. Most Ha emitters have a spiral morphology (41% +/- 8% in clusters, 51% +/- 8% in the field), followed by mergers/interactions (28% +/- 8%, 31% +/- 7%, respectively) and early-type galaxies (remarkably as high as 29% +/- 8% in clusters and 15% +/- 6% in the field). A diversity of Ha morphologies is detected, suggesting a diversity of physical processes. In clusters, 30% +/- 8% of the galaxies present a regular morphology, mostly consistent with star formation diffused uniformly across the stellar population (mostly in the disk component, when present). The second most common morphology (28% +/- 8%) is asymmetric/jellyfish, consistent with ram-pressure stripping or other non-gravitational processes in 18% +/- 8% of the cases. Ram-pressure stripping appears significantly less prominent in the field (2% +/- 2%), where the most common morphology/mechanism appears to be consistent with minor gas-rich mergers or clump accretion. This work demonstrates that while environment-specific mechanisms affect galaxy evolution at this redshift, they are diverse and their effects are subtle. A full understanding of this complexity requires larger samples and detailed and spatially resolved physical models.