zCOSMOS is a large redshift survey that is being undertaken in the COSMOS field using 600 hours of observation with the VIMOS spectrograph on the 8-m VLT. The survey is designed to characterise the environments of COSMOS galaxies from the 100 kpc scales of galaxy groups up to the 100 Mpc scale of the cosmic web and to produce diagnostic information on galaxies and active galactic nuclei. The zCOSMOS survey consists of two parts: (a) zCOSMOS-bright, a magnitude-limited I-band I AB < 22.5 sample of about 20,000 galaxies with 0.1 < z < 1.2 covering the whole 1.7 deg 2 COSMOS ACS field, for which the survey parameters at z ~ 0.7 are designed to be directly comparable to those of the 2dFGRS at z ~ 0.1; and (b) zCOSMOS-deep, a survey of approximately 10,000 galaxies selected through colourselection criteria to have 1.4 < z < 3.0, within the central 1 deg 2 . This paper describes the survey design and the construction of the target catalogues, and briefly outlines the observational program and the data pipeline. In the first observing season, spectra of 1303 zCOSMOS-bright targets and of 977 zCOSMOS-deep targets have been obtained. These are briefly analysed to demonstrate the characteristics that may be expected from zCOSMOS, and particularly zCOSMOS-bright, when it is finally completed between 2008-2009. The power of combining spectroscopic and photometric redshifts is demonstrated, especially in correctly identifying the emission line in single-line spectra and in determining which of the less reliable spectroscopic redshifts are correct and which are incorrect. These techniques bring the overall success rate in the zCOSMOS-bright so far to almost 90% and to above 97% in the 0.5 < z < 0.8 redshift range. Our zCOSMOS-deep spectra demonstrate the power of our selection techniques to isolate high redshift galaxies at 1.4 < z < 3.0 and of VIMOS to measure their redshifts using ultraviolet absorption lines.

We present the Spectroscopic Imaging survey in the Near-infrared with SINFONI (SINS) of high redshift galaxies. With 80 objects observed and 63 detected in at least one rest-frame optical nebular emission line, mainly Hα, SINS represents the largest survey of spatially-resolved gas kinematics, morphologies, and physical properties of star-forming galaxies at z ∼ 1−3. We describe the selection of the targets, the observations, and the data reduction. We then focus on the "SINS Hα sample," consisting of 62 rest-UV/optically-selected sources at 1.3 < z < 2.6 for which we targeted primarily the Hα and [N II] emission lines. Only ≈ 30% of this sample had previous near-IR spectroscopic observations. The galaxies were drawn from various imaging surveys with different photometric criteria; as a whole, the SINS Hα sample covers a reasonable representation of massive M ⋆ 10 10 M ⊙ star-forming galaxies at z ≈ 1.5 − 2.5, with some bias towards bluer systems compared to pure K-selected samples due to the requirement of secure optical redshift. The sample spans two orders of magnitude in stellar mass and in absolute and specific star formation rates, with median values ≈ 3 × 10 10 M ⊙ , ≈ 70 M ⊙ yr −1 , and ≈ 3 Gyr −1 . The ionized gas distribution and kinematics are spatially resolved on scales ranging from ≈ 1.5 kpc for adaptive optics assisted observations to typically ≈ 4 − 5 kpc for seeing-limited data. The Hα morphologies tend to be irregular and/or clumpy. About one-third of the SINS Hα sample galaxies are rotation-dominated yet turbulent disks, another third comprises compact and velocity dispersion-dominated objects, and the remaining galaxies are clear interacting/merging systems; the fraction of rotation-dominated systems increases among the more massive part of the sample. The Hα luminosities and equivalent widths suggest on average roughly twice higher dust attenuation towards the H II regions relative to the bulk of the stars, and comparable current and past-averaged star formation rates.

We present the “SINS/zC-SINF AO survey” of 35 star-forming galaxies, the largest sample with deep adaptive optics (AO)–assisted near-infrared integral field spectroscopy at z ∼ 2. The observations, taken with SINFONI at the Very Large Telescope, resolve the Hα and [N ii] emission and kinematics on scales of ∼1.5 kpc. The sample probes the massive (M ⋆ ∼ 2 × 109 − 3 × 1011 M ⊙), actively star-forming (SFR ∼ 10–600 M ⊙ yr−1) part of the z ∼ 2 galaxy population over a wide range of colors ((U − V)rest ∼ 0.15–1.5 mag) and half-light radii (R e,H ∼ 1–8.5 kpc). The sample overlaps largely with the “main sequence” of star-forming galaxies in the same redshift range to a similar K AB = 23 mag limit; it has ∼0.3 dex higher median specific SFR, ∼0.1 mag bluer median (U − V)rest color, and ∼10% larger median rest-optical size. We describe the observations, data reduction, and extraction of basic flux and kinematic properties. With typically 3–4 times higher resolution and 4–5 times longer integrations (up to 23 hr) than the seeing-limited data sets of the same objects, the AO data reveal much more detail in morphology and kinematics. The complete AO observations confirm the majority of kinematically classified disks and the typically elevated disk velocity dispersions previously reported based on subsets of the data. We derive typically flat or slightly negative radial [N ii]/ gradients, with no significant trend with global galaxy properties, kinematic nature, or the presence of an AGN. Azimuthal variations in [N ii]/ are seen in several sources and are associated with ionized gas outflows and possibly more metal-poor star-forming clumps or small companions. The reduced AO data are made publicly available (http://www.mpe.mpg.de/ir/SINS/SINS-zcSINF-data).

Context. Clusters of galaxies represent important laboratories for studying galaxy evolution and formation. Well established and relaxed clusters are known below z < 1.4, as well as, clusters in formation found close to radio galaxies at z > 2, but the in-between redshift range, during which clusters are expected to undergo significant changes, is almost unexplored. Aims. By studying a galaxy overdensity in redshift and angular distribution at z = 1.6, uncovered in the Galaxy Mass Assembly ultra-deep Spectroscopic Survey (GMASS), we provide insight into the evolution of cluster galaxies at high redshift. Methods. We present a study of the significance of the galaxy overdensity at z = 1.6, Cl 0332-2742, its velocity dispersion, and X-ray emission. We identify the colour bimodality of the cluster members and compare the properties of members of Cl 0332-2742 with galaxies outside the overdensity. Results. From the redshifts of the 42 overdensity members, we measure a velocity dispersion of 500 km s −1 . We conservatively estimate the overdensity in redshift space for the spike at z = 1.6 in the GMASS field to be 8.3 ± 1.5. A map of the surface density of galaxies at z = 1.6 in the GMASS field shows that its structure is irregular with several filaments and local overdensities. The differences in the physical properties of Cl 0332-2742 member and field galaxies agree with the latest hierarchical galaxy formation models: for overdensity members, the star formation rate (SFR), and specific SFR, is approximately 50% lower than for the field galaxies; overdensity galaxies are twice the age, on average, of field galaxies; and there is a higher proportion of both massive (M > 10 10.7 M ), and early-type galaxies, inside Cl 0332-2742 than in the field. Among the 42 members, seven have spectra consistent with being passively evolving, massive galaxies. These are all located within an area where the surface density of z = 1.6 galaxies is highest. In a z − J colour-magnitude diagram, the photometric data of these early-type galaxies are in close agreement with a theoretical red sequence of a galaxy cluster at redshift z = 1.6, which formed most of its stars in a short burst of star formation at z ∼ 3. Conclusions. We conclude that the redshift spike at z = 1.6 in the GMASS field represents a sheet-like structure in the cosmic web, and that the area with the highest surface density within this structure, containing already seven passively evolving galaxies, will evolve into a cluster of galaxies at a later time.

Context. Ultra-deep imaging of small parts of the sky has revealed many populations of distant galaxies, providing insight into the early stages of galaxy evolution. Spectroscopic follow-up has mostly targeted galaxies with strong emission lines at z > 2 or concentrated on galaxies at z < 1. Aims. The populations of both quiescent and actively star-forming galaxies at 1 < z < 2 are still under-represented in our general census of galaxies throughout the history of the Universe. In the light of galaxy formation models, however, the evolution of galaxies at these redshifts is of pivotal importance and merits further investigation. In addition, photometry provides only limited clues about the nature and evolutionary status of these galaxies.We therefore designed a spectroscopic observing campaign of a sample of both massive, quiescent and star-forming galaxies at z > 1.4. Methods. To determine redshifts and physical properties, such as metallicity, dust content, dynamical masses, and star formation history, we performed ultra-deep spectroscopy with the red-sensitive optical spectrograph FORS2 at the Very Large Telescope. We first constructed a sample of objects, within the CDFS/GOODS area, detected at 4.5 μm, to be sensitive to stellar mass rather than star formation intensity. The spectroscopic targets were selected with a photometric redshift constraint (z > 1.4) and magnitude constraints (B AB < 26, I AB < 26.5), which should ensure that these are faint, distant, and fairly massive galaxies. Results. We present the sample selection, survey design, observations, data reduction, and spectroscopic redshifts. Up to 30 h of spectroscopy of 174 spectroscopic targets and 70 additional objects enabled us to determine 210 redshifts, of which 145 are at z > 1.4. The redshift distribution is clearly inhomogeneous with several pronounced redshift peaks. From the redshifts and photometry, we deduce that the BzK selection criteria are efficient (82%) and suffer low contamination (11%). Several papers based on the GMASS survey show its value for studies of galaxy formation and evolution. We publicly release the redshifts and reduced spectra. In combination with existing and on-going additional observations in CDFS/GOODS, this data set provides a legacy for future studies of distant galaxies.

We present the analysis of Hubble Space Telescope (HST) J-and H-band imaging for 29 galaxies on the star-forming main-sequence at z ∼ 2, which have adaptive optics Very Large Telescope SINFONI integral field spectroscopy from our SINS/zC-SINF program. The SINFONI Hα data resolve the ongoing star formation and the ionized gas kinematics on scales of 1 − 2 kpc; the NIR images trace the galaxies' rest frame optical morphologies and distributions of stellar mass in old stellar populations at a similar resolution. The global light profiles of most galaxies show disk-like properties well described by a single Sérsic profile with n ∼ 1, with only ∼ 15% requiring a high n > 3 Sérsic index, all more massive than 10 10 M . In bulge+disk fits, about 40% of galaxies have a measurable bulge component in the light profiles, with ∼ 15% showing a substantial bulge-to-total ratio B/T 0.3. This is a lower limit to the frequency of z ∼ 2 massive galaxies with a developed bulge component in stellar mass because it could be hidden by dust and/or outshined by a thick actively star-forming disk component. The galaxies' rest-optical half-light radii range between 1 and 7 kpc, with a median of 2.1 kpc, and lie slightly above the size-mass relation at these epochs reported in the literature. This is attributed to differences in sample selection and definitions of size and/or mass measurements. The (u − g) rest color gradient and scatter within individual z ∼ 2 massive galaxies with 10 11 M are as high as in z = 0 low-mass, late-type galaxies and are consistent with the high star formation rates of massive z ∼ 2 galaxies being sustained at large galactocentric distances.

Abstract.We report the discovery of a Lyman α emitting galaxy at z = 6.518. The single line was found in the 43 arcmin 2 VLT/FORS field by slitless spectroscopy limited to the atmospheric window at λ ∼ 9100 Å (sampling Lyα at 6.4 < z < 6.6). Its counterpart is undetected in a deep I band image and the line has an asymmetric appearance in a deeper follow-up spectrum. There are no plausible line identifications except for Lyα with a flux of 1.9 × 10 −17 erg cm −2 s −1 and rest frame equivalent width >80 Å. The lower limit to the star formation rate density at z = 6.5 derived from our complete sample is 5 × 10 −4 M yr −1 Mpc −3 , consistent with measurements in the Subaru Deep Field and Hubble Ultra Deep Field but approximately ten times higher than in the Large Area Lyman Alpha survey. This Lyα emitter is among the very small sample of highest redshift galaxies known.

We describe the scientific motivations, the mission concept and the instrumentation of SPACE, a class-M mission proposed for concept study at the first call of the ESA Cosmic-Vision 2015-2025 planning cycle. SPACE aims to produce the largest three-dimensional evolutionary map of the Universe over the past 10 billion years by taking near-IR spectra and measuring redshifts for more than half a billion galaxies at 0 < z < 2 down to AB ∼ 23 over 3π sr of the sky. In addition, SPACE will also target a smaller sky field, performing a deep spectroscopic survey of millions of galaxies to AB ∼ 26 and at 2 < z < 10+. These goals are unreachable with ground-based observations due to the ≈500 times higher sky background (see e.g. Aldering, LBNL report number LBNL-51157, 2001). To achieve the main science objectives, SPACE will use a 1.5 m diameter RitcheyChretien telescope equipped with a set of arrays of Digital Micro-mirror Devices covering a total field of view of 0.4 deg 2 , and will perform large-multiplexing multi-object spectroscopy (e.g. ≈6000 targets per pointing) at a spectral resolution of R∼400 as well as diffraction-limited imaging with continuous coverage from Owing to the depth, redshift range, volume coverage and quality of its spectra, SPACE will reveal with unique sensitivity most of the fundamental cosmological signatures, including the power spectrum of density fluctuations and its turnover. SPACE will also place high accuracy constraints on the dark energy equation of state parameter and its evolution by measuring the baryonic acoustic oscillations imprinted when matter and radiation decoupled, the distanceluminosity relation of cosmological supernovae, the evolution of the cosmic expansion rate, the growth rate of cosmic large-scale structure, and high-z galaxy clusters. The datasets from the SPACE mission will represent a long lasting legacy for the whole astronomical community whose data will be mined for many years to come. Keywords