We present results from a low-resolution spectroscopic survey for 21 galaxy clusters at 0.4 < z < 0.8 selected from the ESO Distant Cluster Survey. We measured spectra using the low-dispersion prism in IMACS on the Magellan Baade telescope and calculate redshifts with an accuracy of sigma(z) = 0.007. We find 1763 galaxies that are brighter than R = 22.9 in the large-scale cluster environs. We identify the galaxies expected to be accreted by the clusters as they evolve to z = 0 using spherical infall models and find that similar to 30%-70% of the z = 0 cluster population lies outside the virial radius at z similar to 0.6. For analogous clusters at z = 0, we calculate that the ratio of galaxies that have fallen into the clusters since z similar to 0.6 to those that were already in the core at that redshift is typically between similar to 0.3 and 1.5. This wide range of ratios is due to intrinsic scatter and is not a function of velocity dispersion, so a variety of infall histories is to be expected for clusters with current velocity dispersions of 300 km s(-1) less than or similar to sigma less than or similar to 1200 km s(-1). Within the infall regions of z similar to 0.6 clusters, we find a larger red fraction of galaxies than in the field and greater clustering among red galaxies than blue. We interpret these findings as evidence of "preprocessing," where galaxies in denser local environments have their star formation rates affected prior to their aggregation into massive clusters, although the possibility of backsplash galaxies complicates the interpretation.

Aims. The aim of this work is to investigate the physical, structur al and evolutionary properties of old, passive galaxies at z> 1.4 and to place new constraints on massive galaxy formation and evo lution. Methods. We combine ultradeep optical spectroscopy from the GMASS pr oject (Galaxy Mass Assembly ultradeep Spectroscopic Survey) with GOODS multi-band (optical to mid–infrared) photomet ry and HST imaging to study a sample of spectroscopically identified passive galaxies at 1 .39< z< 1.99 selected fromSpitzer Space Selescope imaging at 4.5μm. Results. A stacked spectrum with an equivalent integration time of ∼ 500 hours was obtained and compared with libraries of synthe tic stellar population spectra. The stacked spectrum is public ly released. The spectral and photometric SED properties in dicate very weak or absent star formation, moderately old stellar ages of ≈1 Gyr (for solar metallicity) and stellar masses in the range of 10 M⊙, thus implying that the major star formation and assembly pro cesses for these galaxies occurred at z > 2. No X-ray emission was found neither from individual galaxies nor from a stacking a nalysis of the sample. Only one galaxy shows a marginal detec tion at 24μm. These galaxies have morphologies that are predominantly compact and spheroidal. However, their sizes ( Re . 1 kpc) are much smaller than those of spheroids in the present–day Universe . Their stellar mass surface densities are consequently hig her by≈1 dex if compared to spheroids at z≈ 0 with the same mass. Their rest-frame B-band surface brightness scales with the e ff ctive radius, but the offset with respect to the surface brightness of the local Korme ndy relation is too large to be explained by simple passive ev olution. At z≈ 1, a larger fraction of passive galaxies follows the z≈ 0 size – mass relation. Superdense relics with Re ≈ 1 kpc are extremely rare atz ≈ 0 with respect toz > 1, and absent if Re < 1 kpc. Because of the similar sizes and mass densities, we sug ge t that the superdense passive galaxies at 1 < z < 2 are the remnants of the powerful starbursts occurring in su bmillimeter–selected galaxies at z > 2. The results are compared with theoretical models and the m ain i plications discussed in the framework of massive gala xy formation and evolution.

A major question in galaxy formation is how the gas supply that fuels activity in galaxies is modulated by their environment. We use spectroscopy of a set of well-characterized clusters and groups at 0.4 < z < 0.8 from the ESO Distant Cluster Survey and compare it to identically selected field galaxies. Our spectroscopy allows us to isolate galaxies that are dominated by old stellar populations. Here we study a stellar-mass-limited sample (log(M*/M-circle dot) > 10.4) of these old galaxies with weak [O II] emission. We use line ratios and compare to studies of local early-type galaxies to conclude that this gas is likely excited by post-AGB stars and hence represents a diffuse gas component in the galaxies. For cluster and group galaxies the fraction with EW([O II]) > 5 angstrom is f([O II]) = 0.08(-0.03)(+0.02) and f([O II]) = 0.06(-0.04)(+0.07), respectively. For field galaxies we find f([O II]) = 0.2 (+0.07)(-0.06), representing a 2.8 sigma difference between the [O II] fractions for old galaxies between the different environments. We conclude that a population of old galaxies in all environments has ionized gas that likely stems from stellar mass loss. In the field galaxies also experience gas accretion from the cosmic web, and in groups and clusters these galaxies have had their gas accretion shut off by their environment. Additionally, galaxies with emission preferentially avoid the virialized region of the cluster in position-velocity space. We discuss the implications of our results, among which is that gas accretion shutoff is likely effective at group halo masses (log M/M-circle dot > 12.8) and that there are likely multiple gas removal processes happening in dense environments.

We study the evolution of spectral early-type galaxies in clusters, groups and the field up to redshift 0.9 using the EDisCS dataset. We measure Re, Ie, and sigma for 154 cluster and 68 field galaxies. We study the evolution of the zero point of the fundamental plane (FP) and confirm results in the literature, but now also for the low cluster velocity dispersion regime. The mass-to-light ratio varies as Delta log M/L_B=(-0.54+-0.01)z=(-1.61+-0.01)log(1+z) in clusters, independent of their velocity dispersion. The evolution is stronger (Delta log M/L_B=(-0.76+-0.01)z=(-2.27+-0.03)log(1+z)) for field galaxies. The FP residuals correlate with galaxy mass and become progressively negative at low masses. The effect is visible at z>=0.7 for cluster galaxies and at z>=0.5 for field galaxies. We investigate the size evolution of our galaxy sample. We find that the half-luminosity radius for a galaxy with a dynamical or stellar mass of 2x10^11 Msol varies as (1+z)^{-1.0+-0.3} for both cluster and field galaxies. At the same time, stellar velocity dispersions grow with redshift, as (1+z)^{0.59+-0.10} at constant dynamical mass, and as (1+z)^{0.34+- 0.14} at constant stellar mass. The measured size evolution reduces to Re (1+z)^{-0.5+- 0.2} and sigma (1+z)^{0.41+-0.08}, at fixed dynamical masses, and Re (1+z)^{-0.68+-0.4} and sigma (1+z)^{0.19+-0.10}, at fixed stellar masses, when the progenitor bias (galaxies that locally are of spectroscopic early-type, but not very old, disappear from the EDisCS high-redshift sample; these galaxies tend to be large in size) is taken into account. Taken together, the variations in size and velocity dispersion imply that the luminosity evolution with redshift derived from the zero point of the FP is somewhat milder than that derived without taking these variations into account.

We discovered a mistake in Eqs. (7) and (10) of Saglia et al. (2010, A&A, 524, A6), which propagates to Tables 8 and 9 and Fig. 25. We revise the tables, the figure and the affected statements in the paper. As a result, the reduction in the luminosity evolution due to the effects of the size and velocity dispersion evolution is smaller than claimed in Saglia et al. (2010).

We used the PdBI to map a sample of 15 SMGs in the COSMOS field at the wavelength of 1.3 mm. The target SMGs were originally discovered in the JCMT/AzTEC 1.1 mm continuum survey at S/N=4-4.5. This paper presents, for the first time, interferometric millimetre-wavelength observations of these sources. The angular resolution of our observations, 1.8", allowed us to accurately determine the positions of the target SMGs. Using a detection threshold of S/N>4.5 regardless of multiwavelength counterpart association, and 4<S/N<=4.5 if a multiwavelength counterpart within 1.5" is also present, the total number of detections in our survey is 22. Three of our detected SMGs (AzTEC21, 27, and 28; which corresponds to 20 angular resolution, and these sources are found to have elongated or clumpy morphologies and/or multiple components. Using optical to NIR photometric redshifts, available spectroscopic redshifts, and redshifts estimated from the radio-to-submm spectral index we infer a median redshift of z̃=3.20±0.25 for our sample. To study the overall multiplicity and redshift distribution of flux-limited samples of SMGs we combined these sources with the 15 brightest AzTEC SMGs detected at 1.1 mm, AzTEC1-15, and studied previously. This constitutes a complete, flux- and S/N-limited 1.1-mm selected sample. We find that the median redshift for the 15 brightest AzTEC SMGs (z̃=3.05±0.44) is consistent with that for AzTEC16-30. This conforms to recent observational findings that SMGs do not exhibit any significant trend between the redshift and (sub)mm flux density. For the combined AzTEC1-30 sample we derive a median redshift of z̃=3.17±0.27, consistent with previous results based on mm-selected samples. We further infer that within the combined AzTEC1-30 sample ∼25±9% of sources separate into multiple components.

We used the Plateau de Bure Interferometer (PdBI) to map a sample of 15 submillimetre galaxies (SMGs) in the COSMOS field at the wavelength of 1.3 mm. The target SMGs were originally discovered in the James Clerk Maxwell Telescope (JCMT)/AzTEC 1.1 mmcontinuum survey at S/N-1.1mm = 4-4.5. This paper presents, for the first time, interferometric millimetre-wavelength observations of these sources. The angular resolution of our observations, similar to 1 ''.8, allowed us to accurately determine the positions of the target SMGs. Using a detection threshold of S/N-1.3mm > 4.5 regardless of multiwavelength counterpart association, and 4 < S/N-1.3 mm <= 4.5 if a multiwavelength counterpart within 1 ''.5 is also present, the total number of detections in our survey is 22. The most significant PdBI detection of S/N-1.3 (mm) = 10.3 is towards AzTEC19. Three of our detected SMGs (AzTEC21, 27, and 28; which corresponds to 20%) are marginally resolved at our angular resolution, and these sources are found to have elongated or clumpy morphologies and/or multiple components. Using optical to near-infrared photometric redshifts, available spectroscopic redshifts, and redshifts estimated from the radio-to-submm spectral index we infer a median redshift of <(z)over tilde> = 3.20 +/- 0.25 for our sample. To study the overall multiplicity and redshift distribution of flux-limited samples of SMGs we combined these sources with the 15 brightest JCMT/AzTEC SMGs detected at 1.1 mm, AzTEC1-15, and studied previously. This constitutes a complete, flux-and S/N-limited 1.1-mm selected sample. We find that the median redshift for the 15 brightest JCMT/AzTEC SMGs ((z) over tilde = 3.05 +/- 0.44) is consistent with that for AzTEC16-30. This conforms to recent observational findings that SMGs do not exhibit any significant trend between the redshift and (sub) mm flux density. For the combined AzTEC1-30 sample we derive a median redshift of (z) over tilde = 3.17 +/- 0.27, consistent with previous results based on mm-selected samples. We further infer that within the combined AzTEC1-30 sample similar to 25 +/- 9% of sources separate into multiple components.

We compute optical galaxy luminosity functions (GLFs) in the B, V, R, and I rest-frame bands for one of the largest medium-to-high-redshift (0.4 < z < 0.9) cluster samples to date in order to probe the abundance of faint galaxies in clusters. We also study how the GLFs depend on cluster redshift, mass, and substructure, and compare the GLFs of clusters with those of the field. We separately investigate the GLFs of blue and red-sequence (RS) galaxies to understand the evolution of different cluster populations. We find that the shapes of our GLFs are similar for the B, V, R, and I bands with a drop at the red GLF faint end that is more pronounced at high-redshift: alpha(red) ~ -0.5 at 0.40 < z < 0.65 and alpha(red) > 0.1 at 0.65 < z < 0.90. The blue GLFs have a steeper faint end (alpha(blue) ~ -1.6) than the red GLFs, that appears to be independent of redshift. For the full cluster sample, blue and red GLFs intersect at M(V) = -20, M(R) = -20.5, and M(I) = -20.3. A study of how galaxy types evolve with redshift shows that late type galaxies appear to become early types between z ~ 0.9 and today. Finally, the faint ends of the red GLFs of more massive clusters appear to be richer than less massive clusters, which is more typical of the lower redshift behaviour. Our results indicate that our clusters form at redshifts higher than z = 0.9 from galaxy structures that already have an established red sequence. Late type galaxies then appear to evolve into early types, enriching the red-sequence between this redshift and today. This effect is consistent with the evolution of the faint end slope of the red-sequence and the galaxy type evolution that we find. Finally, faint galaxies accreted from the field environment at all redshifts might have replaced the blue late type galaxies that converted into early types, explaining the lack of evolution in the faint end slopes of the blue GLFs.

The role of major mergers in galaxy and black hole formation is not well-constrained. To help address this, we develop an automated method to identify late-stage galaxy mergers before coalescence of the galactic cores. The resulting sample of mergers is distinct from those obtained using pair-finding and morphological indicators. Our method relies on median-filtering of high-resolution images to distinguish two concentrated galaxy nuclei at small separations. This method does not rely on low surface brightness features to identify mergers, and is therefore reliable to high redshift. Using mock images, we derive statistical contamination and incompleteness corrections for the fraction of late-stage mergers. The mock images show that our method returns an uncontaminated ( < 10 % ?> ) sample of mergers with projected separations between 2.2 and 8 kpc ?> out to z ∼ 1 ?> . We apply our new method to a magnitude-limited ( m FW 814 < 23 ?> ) sample of 44,164 galaxies from the COSMOS HST/ACS catalog. Using a mass-complete sample with log M * / M ⊙ > 10.6 ?> and 0.25 < z ≤ 1.00 ?> , we find ∼ 5 % ?> of systems are late-stage mergers. Correcting for incompleteness and contamination, the fractional merger rate increases strongly with redshift as R merge ∝ ( 1 + z ) 3.8 ± 0.9 ?> , in agreement both with earlier studies and with dark matter halo merger rates. Separating the sample into star-forming and quiescent galaxies shows that the merger rate for star-forming galaxies increases strongly with redshift, ( 1 + z ) 4.5 ± 1.3 ?> , while the merger rate for quiescent galaxies is consistent with no evolution, ( 1 + z ) 1.1 ± 1.2 ?> . The merger rate also becomes steeper with decreasing stellar mass. Limiting our sample to galaxies with spectroscopic redshifts from zCOSMOS, we find that the star formation rates and X-ray selected active galactic nucleus (AGN) activity in likely late-stage mergers are higher by factors of ∼ 2 ?> relative to those of a control sample. Combining our sample with more widely separated pairs, we find that 8 ± 5 % ?> of star formation and 20 ± 8 % ?> of AGN activity are triggered by close encounters ( < 143 kpc ?> ) or mergers, providing additional evidence that major mergers are not the only channels for star formation and black hole growth.

Context. Constraints on the mass distribution in high-redshift clusters of galaxies are currently not very strong.Aims. We aim to constrain the mass profile, M(r), and dynamical status of the z similar to 0.8 LCDCS 0504 cluster of galaxies that is characterized by prominent giant gravitational arcs near its center.Methods. Our analysis is based on deep X-ray, optical, and infrared imaging as well as optical spectroscopy, collected with various instruments, which we complemented with archival data. We modeled the mass distribution of the cluster with three different mass density profiles, whose parameters were constrained by the strong lensing features of the inner cluster region, by the X-ray emission from the intracluster medium, and by the kinematics of 71 cluster members.Results. We obtain consistent M(r) determinations from three methods based on kinematics (dispersion-kurtosis, caustics, and MAMPOSSt), out to the cluster virial radius, similar or equal to 1.3 Mpc and beyond. The mass profile inferred by the strong lensing analysis in the central cluster region is slightly higher than, but still consistent with, the kinematics estimate. On the other hand, the X-ray based M(r) is significantly lower than the kinematics and strong lensing estimates. Theoretical predictions from Lambda CDM cosmology for the concentration-mass relation agree with our observational results, when taking into account the uncertainties in the observational and theoretical estimates. There appears to be a central deficit in the intracluster gas mass fraction compared with nearby clusters.Conclusions. Despite the relaxed appearance of this cluster, the determinations of its mass profile by different probes show substantial discrepancies, the origin of which remains to be determined. The extension of a dynamical analysis similar to that of other clusters of the DAFT/FADA survey with multiwavelength data of sufficient quality will allow shedding light on the possible systematics that affect the determination of mass profiles of high-z clusters, which is possibly related to our incomplete understanding of intracluster baryon physics.

Context. The DAFT/FADA survey is based on the study of similar to 90 rich (masses found in the literature >2 x 10(14) M-circle dot) and moderately distant clusters (redshifts 0.4 < z < 0.9), all with HST imaging data available. This survey has two main objectives: to constrain dark energy (DE) using weak lensing tomography on galaxy clusters and to build a database (deep multi-band imaging allowing photometric redshift estimates, spectroscopic data, X-ray data) of rich distant clusters to study their properties.Aims. We analyse the structures of all the clusters in the DAFT/FADA survey for which XMM-Newton and/or a sufficient number of galaxy redshifts in the cluster range are available, with the aim of detecting substructures and evidence for merging events. These properties are discussed in the framework of standard cold dark matter (Lambda CDM) cosmology.Methods. In X-rays, we analysed the XMM-Newton data available, fit a beta-model, and subtracted it to identify residuals. We used Chandra data, when available, to identify point sources. In the optical, we applied a Serna & Gerbal (SG) analysis to clusters with at least 15 spectroscopic galaxy redshifts available in the cluster range. We discuss the substructure detection efficiencies of both methods.Results. XMM-Newton data were available for 32 clusters, for which we derive the X-ray luminosity and a global X-ray temperature for 25 of them. For 23 clusters we were able to fit the X-ray emissivity with a beta-model and subtract it to detect substructures in the X-ray gas. A dynamical analysis based on the SG method was applied to the clusters having at least 15 spectroscopic galaxy redshifts in the cluster range: 18 X-ray clusters and 11 clusters with no X-ray data. The choice of a minimum number of 15 redshifts implies that only major substructures will be detected. Ten substructures were detected both in X-rays and by the SG method. Most of the substructures detected both in X-rays and with the SG method are probably at their first cluster pericentre approach and are relatively recent infalls. We also find hints of a decreasing X-ray gas density profile core radius with redshift.Conclusions. The percentage of mass included in substructures was found to be roughly constant with redshift values of 5-15%, in agreement both with the general CDM framework and with the results of numerical simulations. Galaxies in substructures show the same general behaviour as regular cluster galaxies; however, in substructures, there is a deficiency of both late type and old stellar population galaxies. Late type galaxies with recent bursts of star formation seem to be missing in the substructures close to the bottom of the host cluster potential well. However, our sample would need to be increased to allow a more robust analysis.

Aims. We investigate the morphological properties of 494 galaxies selected from the Galaxy Mass Assembly ultra-deep Spectroscopic Survey (GMASS) at z > 1, primarily in their optical rest frame, using Hubble Space Telescope (HST) infrared images, from the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS).Methods. The morphological analysis of Wield Field Camera (WFC3) H-160 band images was performed using two different methods: a visual classification identifying traditional Hubble types, and a quantitative analysis using parameters that describe structural properties, such as the concentration of light and the rotational asymmetry. The two classifications are compared. We then analysed how apparent morphologies correlate with the physical properties of galaxies.Results. The fractions of both elliptical and disk galaxies decrease between redshifts z similar to 1 to z similar to 3, while at z > 3 the galaxy population is dominated by irregular galaxies. The quantitative morphological analysis shows that, at 1 < z < 3, morphological parameters are not as effective in distinguishing the different morphological Hubble types as they are at low redshift.No significant morphological k-correction was found to be required for the Hubble type classification, with some exceptions.In general, different morphological types occupy the two peaks of the (U - B) rest colour bimodality of galaxies: most irregulars occupy the blue peak, while ellipticals are mainly found in the red peak, though with some level of contamination. Disks are more evenly distributed than either irregulars and ellipticals. We find that the position of a galaxy in a UVJ diagram is related to its morphological type: the "quiescent" region of the plot is mainly occupied by ellipticals and, to a lesser extent, by disks.We find that only similar to 33% of all morphological ellipticals in our sample are red and passively evolving galaxies, a percentage that is consistent with previous results obtained at z < 1. Blue galaxies morphologically classified as ellipticals show a remarkable structural similarity to red ones.We search for correlations between our morphological and spectroscopic galaxy classifications. Almost all irregulars have a star-forming galaxy spectrum. In addition, the majority of disks show some sign of star-formation activity in their spectra, though in some cases their red continuum is indicative of old stellar populations. Finally, an elliptical morphology may be associated with either passively evolving or strongly star-forming galaxies.Conclusions. We propose that the Hubble sequence of galaxy morphologies takes shape at redshift 2.5 < z < 3. The fractions of both ellipticals and disks decrease with increasing lookback time at z > 1, such that at redshifts z = 2.5-2.7 and above, the Hubble types cannot be identified, and most galaxies are classified as irregular.

We analyse the extended, ionized-gas emission of 24 early-type galaxies (ETGs) at 0 < z < 1 from the ESO Distant Cluster Survey (EDisCS). We discuss different possible sources of ionization and favour star formation as the main cause of the observed emission. 10 galaxies have disturbed gas kinematics, while 14 have rotating gas discs. In addition, 15 galaxies are in the field, while 9 are in the infall regions of clusters. This implies that, if the gas has an internal origin, this is likely stripped as the galaxies get closer to the cluster centre. If the gas instead comes from an external source, then our results suggest that this is more likely acquired outside the cluster environment, where galaxy–galaxy interactions more commonly take place. We analyse the Tully–Fisher relation of the ETGs with gas discs, and compare them to EDisCS spirals. Taking a matched range of redshifts, MB < −20, and excluding galaxies with large velocity uncertainties, we find that, at fixed rotational velocity, ETGs are 1.7 mag fainter in MB than spirals. At fixed stellar mass, we also find that ETGs have systematically lower specific star formation rates than spirals. This study constitutes an important step forward towards the understanding of the evolution of the complex ISM in ETGs by significantly extending the look-back-time baseline explored so far.

We present the analysis of the galaxy stellar mass function in different environments at intermediate redshift (0.3 10^(10.5) M_sun, to study cluster, group, and field galaxies at z=0.3-0.45, and the ESO Distant Cluster Survey (EDisCS), at masses M_ast > 10^(10.2) M_sun, to investigate cluster and group galaxies at z=0.4-0.8. Therefore, in our analysis we include galaxies that are slightly less massive than the Milky Way. Having excluded the brightest cluster galaxies, we show thatthe shape of the mass distribution does not seem to depend on global environment. Our two main results are: (1) Galaxies in the virialized regions of clusters, in groups, and in the field follow a similar mass distribution. (2) Comparing both ICBS and EDisCS mass functions to mass functions in the local Universe, we find evolution from z~0.4-0.6 to z~0.07. The population of low-mass galaxies has proportionally grown with time with respect to that of massive galaxies. This evolution is independent of environment -- the same for clusters and the field. Furthermore, considering only clusters, we find that no differences can be detected neither within the virialized regions, nor when we compare galaxies within and outside the virial radius. Subdividing galaxies in terms of color, in clusters, groups, and field red and blue galaxies are regulated by different mass functions, but comparing separately the blue and red mass functions in different environments, no differences are detected in their shape.

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 mu m, 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.

The relationships between galaxies of intermediate stellar mass and moderate luminosity active galactic nuclei (AGNs) at 110^42.3 erg s^-1 disappear from the blue cloud/green valley where they were hosted predominantly by star-forming systems with disk and irregular morphologies. These results are even clearer when the rest-frame colors are corrected for dust reddening. At z 2.2, the ultraviolet spectra of active galaxies (including two Type 1 AGNs) show possible gas outflows with velocities up to about -500 km s^-1 that are not observed neither in inactive systems at the same redshift, nor at lower redshifts. Such outflows indicate the presence of gas that can move faster than the escape velocities of active galaxies. These results suggest that feedback from moderately luminous AGNs (logL_X<44.5 erg s^-1) played a key role at z> 2 by contributing to outflows capable of ejecting part of the interstellar medium and leading to a rapid decrease in the star formation in host galaxies with stellar masses 10

Context. The study of intracluster light (ICL) can help us to understand the mechanisms taking place in galaxy clusters, and to place constraints on the cluster formation history and physical properties. However, owing to the intrinsic faintness of ICL emission, most searches and detailed studies of ICL have been limited to redshifts z < 0.4.Aims. To help us extend our knowledge of ICL properties to higher redshifts and study the evolution of ICL with redshift, we search for ICL in a subsample of ten clusters detected by the ESO Distant Cluster Survey (EDisCS), at redshifts 0.4 < z < 0.8, that are also part of our DAFT/FADA Survey.Methods. We analyze the ICL by applying the OV WAV package, a wavelet-based technique, to deep HST ACS images in the F814W filter and to V-band VLT/FORS2 images of three clusters. Detection levels are assessed as a function of the diffuse light source surface brightness using simulations.Results. In the F814W filter images, we detect diffuse light sources in all the clusters, with typical sizes of a few tens of kpc (assuming that they are at the cluster redshifts). The ICL detected by stacking the ten F814W images shows an 8 sigma detection in the source center extending over a similar to 50 x 50 kpc(2) area, with a total absolute magnitude of -21.6 in the F814W filter, equivalent to about two L* galaxies per cluster. We find a weak correlation between the total F814W absolute magnitude of the ICL and the cluster velocity dispersion and mass. There is no apparent correlation between the cluster mass-to-light ratio (M/L) and the amount of ICL, and no evidence of any preferential orientation in the ICL source distribution. We find no strong variation in the amount of ICL between z = 0 and z = 0.8. In addition, we find wavelet-detected compact objects (WDCOs) in the three clusters for which data in two bands are available; these objects are probably very faint compact galaxies that in some cases are members of the respective clusters and comparable to the faint dwarf galaxies of the Local Group.Conclusions. We show that the ICL is prevalent in clusters at least up to redshift z = 0.8. In the future, we propose to detect the ICL at even higher redshifts, to determine wether there is a particular stage of cluster evolution where it was stripped from galaxies and spread into the intracluster medium.

Aims. We use rest-frame UV spectroscopy to investigate the properties related to large-scale gas outflow, and both the dust extinction and star-formation rates (SFRs) of a sample of z ∼ 2 star-forming galaxies from the Galaxy Mass Assembly ultradeep Spectroscopic Survey (GMASS). Methods. Dust extinction is estimated from the rest-frame UV continuum slope and used to obtain dust-corrected SFRs for the galaxies in the sample. A composite spectrum is created by averaging all the single spectra of our sample, and the equivalent widths and centroids of the absorption lines associated with the interstellar medium are measured. We then calculate the velocity offsets of these lines relative to the composite systemic velocity, which is obtained from photospheric stellar absorption lines and nebular emission lines. Finally, to investigate correlations between galaxy UV spectral characteristics and galaxy general properties, the sample is divided into two bins that are equally populated, according to the galaxy properties of stellar mass, color excess, and SFR. A composite spectrum for each group of galaxies is then created, and both the velocity offsets and the equivalent widths of the interstellar absorption lines are measured. Results. For the entire sample, we derive a mean value of the continuum slope � β� = −1.11 ± 0.44 (rms). For each galaxy, we calculate the dust extinction from the UV spectrum and then use this to correct the flux measured at 1500 A (rest-frame), before

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 (BAB < 26, IAB < 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.