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Using a sample of four galaxy clusters at 1.35 < z < 1.65 and 10 galaxy clusters at 0.85 < z < 1.35, we measure the environmental quenching timescale, t Q, corresponding to the time required after a galaxy is accreted by a cluster for it to fully cease star formation. Cluster members are selected by a photometric-redshift criterion, and categorized as star-forming, quiescent, or intermediate according to their dust-corrected rest-frame colors and magnitudes. We employ a "delayed-then-rapid" quenching model that relates a simulated cluster mass accretion rate to the observed numbers of each type of galaxy in the cluster to constrain t Q. For galaxies of mass M ∗ 1010.5 M o, we find a quenching timescale of t Q = Gyr in the z ∼ 1.5 cluster sample, and Gyr at z ∼ 1. Using values drawn from the literature, we compare the redshift evolution of t Q to timescales predicted for different physical quenching mechanisms. We find t Q to depend on host halo mass such that quenching occurs over faster timescales in clusters relative to groups, suggesting that properties of the host halo are responsible for quenching high-mass galaxies. Between z = 0 and z = 1.5, we find that t Q evolves faster than the molecular gas depletion timescale and slower than an estimated star formation rate-outflow timescale, but is consistent with the evolution of the dynamical time. This suggests that environmental quenching in these galaxies is driven by the motion of satellites relative to the cluster environment, although due to uncertainties in the atomic gas budget at high redshift, we cannot rule out quenching due to simple gas depletion.

We present Atacama Large Millimeter/submillimeter Array observations of a massive (M_stars~10^11 M_Sun) compact (r_e,UV~100 pc) merger remnant at z=0.66 that is driving a 1000 km/s outflow of cool gas, with no observational trace of an active galactic nucleus (AGN). We resolve molecular gas on scales of approximately 1-2 kpc, and our main finding is the discovery of a wing of blueshifted CO(2-1) emission out to -1000 km/s relative to the stars. We argue that this is the molecular component of a multiphase outflow, expelled from the central starburst within the past 5 Myr through stellar feedback, although we cannot rule out previous AGN activity as a launching mechanism. If the latter is true, then this is an example of a relic multiphase AGN outflow. We estimate a molecular mass outflow rate of approximately 300 M_Sun/yr, or about one third of the 10 Myr-averaged star formation rate. This system epitomizes the multiphase 'blowout' episode following a dissipational major merger - a process that has violently quenched central star formation and supermassive black hole growth., Accepted for publication in ApJ Letters: The Astrophysical Journal Letters, Volume 864, Number 1

Using a sample of 4 galaxy clusters at $1.35 < z < 1.65$ and 10 galaxy clusters at $0.85 < z < 1.35$, we measure the environmental quenching timescale, $t_Q$, corresponding to the time required after a galaxy is accreted by a cluster for it to fully cease star formation. Cluster members are selected by a photometric-redshift criterion, and categorized as star-forming, quiescent, or intermediate according to their dust-corrected rest-frame colors and magnitudes. We employ a "delayed-then-rapid" quenching model that relates a simulated cluster mass accretion rate to the observed numbers of each type of galaxy in the cluster to constrain $t_Q$. For galaxies of mass $M_* \gtrsim 10^{10.5}~ \mathrm{M}_\odot$, we find a quenching timescale of $t_Q=$ 1.24 Gyr in the $z\sim1.5$ cluster sample, and $t_Q=$ 1.50 Gyr at $z\sim1$. Using values drawn from the literature, we compare the redshift evolution of $t_Q$ to timescales predicted for different physical quenching mechanisms. We find $t_Q$ to depend on host halo mass such that quenching occurs over faster timescales in clusters relative to groups, suggesting that properties of the host halo are responsible for quenching high-mass galaxies. Between $z=0$ and $z=1.5$, we find that $t_Q$ evolves faster than the molecular gas depletion timescale and slower than an SFR-outflow timescale, but is consistent with the evolution of the dynamical time. This suggests that environmental quenching in these galaxies is driven by the motion of satellites relative to the cluster environment, although due to uncertainties in the atomic gas budget at high redshift, we cannot rule out quenching due to simple gas depletion.

In this paper we study the colour magnitude relation (CMR) for a sample of 172 morphologically classified elliptical and S0 cluster galaxies from the ESO Distant Cluster Survey (EDisCS) at 0.4 ?z? 0.8. The intrinsic colour scatter about the CMR is very small (= 0.076) in rest frame U V. However there is a small minority of faint early type galaxies (7 per cent) that are significantly bluer than the CMR. We observe no significant dependence of sint with redshift or cluster velocity dispersion. Because our sample is strictly morphologically selected this implies that by the time cluster elliptical and S0 galaxies achieve their morphology the vast majority have already joined the red sequence. The only exception seems to be the very small fraction of faint blue early types. Assuming that the intrinsic colour scatter is due to differences in stellar population ages we estimate the galaxy formation redshift zF of each cluster and find that zF does not depend on the cluster velocity dispersion. However zF increases weakly with cluster redshift within the EDisCS sample. This trend becomes very clear when higher redshift clusters from the literature are included. This suggests that at any given redshift in order to have a population of fully formed ellipticals and S0s they needed to have formed most of their stars ?2 4 Gyr prior to observation. That does not mean that all early type galaxies in all clusters formed at these high redshifts. It means that the ones we see already having early type morphologies also have reasonably old stellar populations. This is partly a manifestation of the `progenitor bias' but also a consequence of the fact that the vast majority of the early type galaxies in clusters (in particular the massive galaxies) were already red (i.e. already had old stellar populations) by the time they achieved their morphology. Elliptical and S0 galaxies exhibit very similar colour scatter implying similar stellar population ages. The scarcity of blue S0s indicates that if they are the descendants of spirals whose star formation has ceased the parent galaxies were already red when they became S0s. This suggests the red spirals found preferentially in dense environments could be the progenitors of these S0s. We also find that fainter early type galaxies finished forming their stars later (i.e. have smaller zF) consistent with the cluster red sequence being built over time and the brightest galaxies reaching the red sequence earlier than fainter ones. Combining the CMR scatter analysis with the observed evolution in the CMR zero point we find that the early type cluster galaxy population must have had their star formation truncated/stopped over an extended period ?t? 1 Gyr.

We discuss the structural and morphological properties of galaxies in a z=1.62 proto-cluster using near-IR imaging data from Hubble Space Telescope Wide Field Camera 3 data of the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS). The cluster galaxies exhibit a clear color-morphology relation: galaxies with colors of quiescent stellar populations generally have morphologies consistent with spheroids, and galaxies with colors consistent with ongoing star formation have disk-like and irregular morphologies. The size distribution of the quiescent cluster galaxies shows a deficit of compact (< 1kpc), massive galaxies compared to CANDELS field galaxies at z=1.6. As a result the cluster quiescent galaxies have larger average effective sizes compared to field galaxies at fixed mass at greater than 90% significance. Combined with data from the literature, the size evolution of quiescent cluster galaxies is relatively slow from z~1.6 to the present, growing as (1+z)^(-0.6+/-0.1). If this result is generalizable, then it implies that physical processes associated with the denser cluster region seems to have caused accelerated size growth in quiescent galaxies prior to z=1.6 and slower subsequent growth at z, Accepted for publication in ApJ. 14 pages in emulateapj format. Replacement includes improvements from referee report, and updates and additions to references

International audience; We present a comprehensive analysis of the stellar population properties and morphologies of red-sequence galaxies in 24 clusters and groups from z˜0.75 to z˜0.45. The dataset, consisting of 215 spectra drawn from the ESO Distant Cluster Survey, constitutes the largest spectroscopic sample at these redshifts for which such an analysis has been conducted. Analysis reveals that the evolution of the stellar population properties of red-sequence galaxies depend on their mass: while the properties of the most massive are well described by passive evolution and high-redshift formation, those of the less massive galaxies are consistent with a more extended star-formation history. We show that these scenarios reproduce the index-σ relations and the galaxy colours. The two main results of this work are: (1) the evolution of the line-strength indices for the red-sequence galaxies can be reproduced if 40% of the galaxies with σ< 175 km s-1 entered the red-sequence between z=0.75 to z=0.45, in agreement with the fraction derived in studies of the luminosity functions; and (2) the percentage of red-sequence galaxies exhibiting early-type morphologies (E and S0) decreases by 20% from z=0.75 to z=0.45. This can be understood if the red-sequence becomes more populated at later times with disc galaxies whose star formation has been quenched. We conclude that the processes quenching star formation do not necessarily produce a simultaneous morphological transformation of the galaxies entering the red-sequence. Based on observations obtained at the ESO Very Large Telescope (VLT) as part of the Large Programme 166.A-0162 (the ESO Distant Cluster Survey). Full Table 3 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/499/47

We present a comprehensive analysis of the stellar population properties (age, metallicity and the alpha-element enhancement [E/Fe]) and morphologies of red-sequence galaxies in 24 clusters and groups from z~0.75 to z~0.45. The dataset, consisting of 215 spectra drawn from the ESO Distant Cluster Survey, constitutes the largest spectroscopic sample at these redshifts for which such an analysis has been conducted. Analysis reveals that the evolution of the stellar population properties of red-sequence galaxies depend on their mass: while the properties of most massive are well described by passive evolution and high-redshift formation, the less massive galaxies require a more extended star formation history. We show that these scenarios reproduce the index-sigma relations as well as the galaxy colours. The two main results of this work are (1) the evolution of the line-strength indices for the red-sequence galaxies can be reproduced if 40% of the galaxies with sigma < 175 km/s entered the red-sequence between z=0.75 to z=0.45, in agreement with the fraction derived in studies of the luminosity functions, and (2) the percentage the red-sequence galaxies exhibiting early-type morphologies (E and S0) decreases by 20% from z=0.75 to z=0.45. This can be understood if the red-sequence gets populated at later times with disc galaxies whose star formation has been quenched. We conclude that the processes quenching star formation do not necessarily produce a simultaneous morphological transformation of the galaxies entering the red-sequence., Accepted for publication in A&A

We present HST NICMOS+ACS and Spitzer IRAC+MIPS observations of 41 galaxies at 2, Comment: Accepted for publication in ApJ

We describe Hubble Space Telescope (HST) imaging of 10 of the 20 ESO Distant Cluster Survey (EDisCS) fields. Each ~40 square arcminute field was imaged in the F814W filter with the Advanced Camera for Surveys Wide Field Camera. Based on these data, we present visual morphological classifications for the ~920 sources per field that are brighter than I_auto=23 mag. We use these classifications to quantify the morphological content of 10 intermediate-redshift (0.5 < z < 0.8) galaxy clusters within the HST survey region. The EDisCS results, combined with previously published data from seven higher redshift clusters, show no statistically significant evidence for evolution in the mean fractions of elliptical, S0, and late-type (Sp+Irr) galaxies in clusters over the redshift range 0.5 < z < 1.2. In contrast, existing studies of lower redshift clusters have revealed a factor of ~2 increase in the typical S0 fraction between z=0.4 and z=0, accompanied by a commensurate decrease in the Sp+Irr fraction and no evolution in the elliptical fraction. The EDisCS clusters demonstrate that cluster morphological fractions plateau beyond z ~ 0.4. They also exhibit a mild correlation between morphological content and cluster velocity dispersion, highlighting the importance of careful sample selection in evaluating evolution. We discuss these findings in the context of a recently proposed scenario in which the fractions of passive (E,S0) and star-forming (Sp,Irr) galaxies are determined primarily by the growth history of clusters., Comment: 18 pages, 7 figures; To be published in ApJ; minor changes made to table labels

We describe Hubble Space Telescope (HST) imaging of 10 of the 20 ESO Distant Cluster Survey (EDisCS) fields. Each ~40 square arcminute field was imaged in the F814W filter with the Advanced Camera for Surveys Wide Field Camera. Based on these data, we present visual morphological classifications for the ~920 sources per field that are brighter than I_auto=23 mag. We use these classifications to quantify the morphological content of 10 intermediate-redshift (0.5 < z < 0.8) galaxy clusters within the HST survey region. The EDisCS results, combined with previously published data from seven higher redshift clusters, show no statistically significant evidence for evolution in the mean fractions of elliptical, S0, and late-type (Sp+Irr) galaxies in clusters over the redshift range 0.5 < z < 1.2. In contrast, existing studies of lower redshift clusters have revealed a factor of ~2 increase in the typical S0 fraction between z=0.4 and z=0, accompanied by a commensurate decrease in the Sp+Irr fraction and no evolution in the elliptical fraction. The EDisCS clusters demonstrate that cluster morphological fractions plateau beyond z ~ 0.4. They also exhibit a mild correlation between morphological content and cluster velocity dispersion, highlighting the importance of careful sample selection in evaluating evolution. We discuss these findings in the context of a recently proposed scenario in which the fractions of passive (E,S0) and star-forming (Sp,Irr) galaxies are determined primarily by the growth history of clusters., 18 pages, 7 figures; To be published in ApJ; minor changes made to table labels

We present XMM-Newton observations of three optically-selected z > 0.6 clusters from the ESO Distant Cluster Survey (EDisCS), comprising the first results of a planned X-ray survey of the full EDisCS high-redshift sample. The EDisCS clusters were identified in the Las Campanas Distant Cluster Survey as surface brightness fluctuations in the optical sky and their masses and galaxy populations are well described by extensive photometric and spectroscopic observations. We detect two of the three clusters in the X-ray and place a firm upper limit on diffuse emission in the third cluster field. We are able to constrain the X-ray luminosity and temperature of the detected clusters and estimate their masses. We find the X-ray properties of the detected EDisCS clusters are similar to those of X-ray-selected clusters of comparable mass and -- unlike other high-redshift, optically-selected clusters -- are consistent with the T - sigma and L_x - sigma relations determined from X-ray selected clusters at low redshift. The X-ray determined mass estimates are generally consistent with those derived from weak lensing and spectroscopic analyses. These preliminary results suggest that the novel method of optical selection used to construct the EDisCS catalog may, like selection by X-ray luminosity, be well-suited for identification of relaxed, high-redshift clusters whose intracluster medium is in place and stable by z ~ 0.8., Comment: MNRAS accepted. 21 pages text, 20 figures, 10 pages tabular data. Version with full resolution figures available at http://www.roe.ac.uk/~cocj/ediscs_fullres.html

We present XMM-Newton observations of three optically-selected z > 0.6 clusters from the ESO Distant Cluster Survey (EDisCS), comprising the first results of a planned X-ray survey of the full EDisCS high-redshift sample. The EDisCS clusters were identified in the Las Campanas Distant Cluster Survey as surface brightness fluctuations in the optical sky and their masses and galaxy populations are well described by extensive photometric and spectroscopic observations. We detect two of the three clusters in the X-ray and place a firm upper limit on diffuse emission in the third cluster field. We are able to constrain the X-ray luminosity and temperature of the detected clusters and estimate their masses. We find the X-ray properties of the detected EDisCS clusters are similar to those of X-ray-selected clusters of comparable mass and -- unlike other high-redshift, optically-selected clusters -- are consistent with the T - sigma and L_x - sigma relations determined from X-ray selected clusters at low redshift. The X-ray determined mass estimates are generally consistent with those derived from weak lensing and spectroscopic analyses. These preliminary results suggest that the novel method of optical selection used to construct the EDisCS catalog may, like selection by X-ray luminosity, be well-suited for identification of relaxed, high-redshift clusters whose intracluster medium is in place and stable by z ~ 0.8., MNRAS accepted. 21 pages text, 20 figures, 10 pages tabular data. Version with full resolution figures available at http://www.roe.ac.uk/~cocj/ediscs_fullres.html

We compare all the available observational data on the redshift evolution of the total stellar mass and star formation rate density in the Universe with the mass and accretion rate density evolution of supermassive black holes, estimated from the hard X-ray selected luminosity function of quasars and active galactic nuclei. We find that on average black hole mass must have been higher at higher redshift for given spheroid stellar mass. Moreover, we find negative redshift evolution of the disk/irregulars to spheroid mass ratio. The total accretion efficiency is constrained to be between 0.06 and 0.12, depending on the exact value of the local SMBH mass density, and on the critical accretion rate below which radiatively inefficient accretion may take place., Comment: 5 pages, 2 color figures. To appear in the proceedings of "Relativistic Astrophysics and Cosmology - Einstein's Legacy" (Eds.: B. Aschenbach, V. Burwitz, G. Hasinger, and B. Leibundgut), 7 - 11 November 2005, Munich, Germany

We present spectroscopic observations of galaxies in 4 clusters at z = 0.7-0.8 and in one cluster at z~0.5 obtained with the FORS2 spectrograph on the VLT as part of the ESO Distant Cluster Survey (EDisCS), a photometric and spectroscopic survey of 20 intermediate to high redshift clusters. We describe our target selection, mask design, observation and data reduction procedures, using these first 5 clusters to demonstrate how our strategies maximise the number of cluster members for which we obtain spectroscopy. We present catalogues containing positions, I-band magnitudes and spectroscopic redshifts for galaxies in the fields of our 5 clusters. These contain 236 cluster members, with the number of members per cluster ranging from 30 to 67. Our spectroscopic success rate, i.e. the fraction of spectroscopic targets which are cluster members, averages 50% and ranges from 30% to 75%. We use a robust biweight estimator to measure cluster velocity dispersions from our spectroscopic redshift samples. We also make a first assessment of substructure within our clusters. The velocity dispersions range from 400 to 1100 km s-1. Some of the redshift distributions are significantly non-Gaussian and we find evidence for significant substructure in two clusters, one at z~0.79 and the other at z~0.54. Both have velocity dispersions exceeding 1000 km s-1 but are clearly not fully virialised; their velocity dispersions may thus be a poor indicator of their masses. The properties of these first 5 EDisCS clusters span a wide range in redshift, velocity dispersion, richness and substructure, but are representative of the sample as a whole. Spectroscopy for the full dataset will allow a comprehensive study of galaxy evolution as a function of cluster environment and redshift., 18 pages, 27 figures, accepted for publication in A&A, Table 4 is available ahead of journal publication by downloading the source files for this astro-ph submission or from first author on request (halliday@pd.astro.it)

We analyse the rest-frame (U-V) colour-magnitude relation for 2 clusters at redshift 0.7 and 0.8, drawn from the ESO Distant Cluster Survey. By comparing with the population of red galaxies in the Coma cluster, we show that the high redshift clusters exhibit a deficit of passive faint red galaxies. Our results show that the red-sequence population cannot be explained in terms of a monolithic and synchronous formation scenario. A large fraction of faint passive galaxies in clusters today has moved onto the red sequence relatively recently as a consequence of the fact that their star formation activity has come to an end at z, 5 pages, 2 figures, to appear in Proc. of IAU Colloq. 195: "Outskirts of Galaxy Clusters: Intense Life in the Suburbs" -- minor typos corrected

The clustering properties of faint K2.At the highest redshifts, 21.7 reach r_0~8 h^-1 Mpc comoving. This is a factor of 3--4 higher than the correlation length of LBGs with similar number densities, down to V_6061.7 colors at 2, Comment: to appear on ApJ, May 1 issue. See also papers by Franx et al. and van Dokkum et al., on this listing

The proposed infrared space interferometry mission Darwin has two main aims: (i) to detect and characterize exo-planets similar to the Earth, and (ii) to carry out astrophysical imaging in the wavelength range 6 - 20 micron at a sensitivity similar to JWST, but at an angular resolution up to 100 times higher. In this contribution we will first briefly discuss the imaging performance of the Darwin mission. We will then discuss how Darwin will contribute in a very significant way to our understanding of the formation and evolution of planets, stars, galaxies, and super-massive black-holes located at the centers of galaxies., Comment: 10 pages, 8 figures, to appear in the proceedings of the conference "Toward Other Earths, Darwin/TPF and the search for extrasolar terrestrial planets", held in Heidelberg, Germany, 22-25 April 2003, ESA SP-539

We present the first results from the Faint Infra-Red Extragalactic Survey of the Hubble Deep Field South (HDF-S). Using a combination of deep near-infrared (NIR) data obtained with the Infrared Spectrograph and Array Camera at the VLT and the WFPC2 Hubble Space Telescope data, we construct a K-band-selected sample which is 50% and 90% complete for and K-s,K-AB less than or equal to 23.5 K-s,K-AB less than or equal to 22.0, respectively, where the magnitudes are measured over a diameter aperture. For z less than or equal to 3, our selection by the K-band flux chooses galaxies based on wavelengths redder than the rest-frame V band, and so selects them in a way that is less dependent on their current star formation rates than selection in the rest-frame UV. We developed a new photometric redshift technique that models the observed spectral energy distribution (SED) with a linear combination of empirical galaxy templates. We tested this technique using 150 spectroscopic redshifts in the Hubble Deep Field North (HDF-N) from the Cohen et al. sample (published in 2000) and found Deltaz/(1 + z) approximate to 0.07 for z 2 we find very luminous galaxies with L-V(rest) h(-2) L. (for Omega (M) = 0.3, Omega (Lambda) = 0.7, H-0 = 100 h km s(-1) Mpc(-1)). Local B-band luminosity functions predict 0.1 galaxies in the redshift range 2 less than or equal to less than or equal to 3.5 and with L-B(rest) greater than or equal to 5 x 10(10) h(-2) L.(,B), but we find nine. The discrepancy can be explained if L-B(*) increases by a factor of 2.4-3.2 with respect to locally determined values. Random errors in the photometric redshift can also play a role, and spectroscopic confirmation of the redshifts of these bright galaxies is required.

A small number of LINERs have been seen to display variable H-alpha emission with a very broad, double-peaked profile. Recent observations with the Hubble Space Telescope indicate that such emission may be a common attribute of LINERs. The double-peaked or double-shouldered line profiles resemble those found in a subset of broad-line radio galaxies. Several lines of argument suggest that such features trace an outer thin accretion disk irradiated by an inner ion torus, in accord with advection-dominated accretion flow (ADAF) models. Variability monitoring of this broad H-alpha component thus may provide a means of testing accretion physics on small scales within these sources., Comment: 7 pages, 2 figures. To appear in "Probing the Physics of Active Galactic Nuclei by Multiwavelength Monitoring"

BigBOSS is a Stage IV ground-based dark energy experiment to study baryon acoustic oscillations (BAO) and the growth of structure with a wide-area galaxy and quasar redshift survey over 14,000 square degrees. It has been conditionally accepted by NOAO in response to a call for major new instrumentation and a high-impact science program for the 4-m Mayall telescope at Kitt Peak. The BigBOSS instrument is a robotically-actuated, fiber-fed spectrograph capable of taking 5000 simultaneous spectra over a wavelength range from 340 nm to 1060 nm, with a resolution R = 3000-4800. Using data from imaging surveys that are already underway, spectroscopic targets are selected that trace the underlying dark matter distribution. In particular, targets include luminous red galaxies (LRGs) up to z = 1.0, extending the BOSS LRG survey in both redshift and survey area. To probe the universe out to even higher redshift, BigBOSS will target bright [OII] emission line galaxies (ELGs) up to z = 1.7. In total, 20 million galaxy redshifts are obtained to measure the BAO feature, trace the matter power spectrum at smaller scales, and detect redshift space distortions. BigBOSS will provide additional constraints on early dark energy and on the curvature of the universe by measuring the Ly-alpha forest in the spectra of over 600,000 2.2 < z < 3.5 quasars. BigBOSS galaxy BAO measurements combined with an analysis of the broadband power, including the Ly-alpha forest in BigBOSS quasar spectra, achieves a FOM of 395 with Planck plus Stage III priors. This FOM is based on conservative assumptions for the analysis of broad band power (kmax = 0.15), and could grow to over 600 if current work allows us to push the analysis to higher wave numbers (kmax = 0.3). BigBOSS will also place constraints on theories of modified gravity and inflation, and will measure the sum of neutrino masses to 0.024 eV accuracy., This report is based on the BigBOSS proposal submission to NOAO in October 2010, and reflects the project status at that time with minor updates

We study the morphological content of a large sample of high-redshift clusters to determine its dependence on cluster mass and redshift. Quantitative morphologies are based on PSF-convolved, 2D bulge+disk decompositions of cluster and field galaxies on deep Very Large Telescope FORS2 images of eighteen, optically-selected galaxy clusters at 0.45 < z < 0.80 observed as part of the ESO Distant Cluster Survey ("EDisCS"). Morphological content is characterized by the early-type galaxy fraction f(et), and early-type galaxies are objectively selected based on their bulge fraction and image smoothness. This quantitative selection is equivalent to selecting galaxies visually classified as E or S0. Changes in early-type fractions as a function of cluster velocity dispersion, redshift and star-formation activity are studied. A set of 158 clusters extracted from the Sloan Digital Sky Survey is analyzed exactly as the distant EDisCS sample to provide a robust local comparison. We also compare our results to a set of clusters from the Millennium Simulation. Our main results are: (1) the early-type fractions of the SDSS and EDisCS clusters exhibit no clear trend as a function of cluster velocity dispersion. (2) Mid-z EDisCS clusters around sigma = 500 km s(-1) have f(et) similar or equal to 0.5 whereas high-z EDisCS clusters have f(et) similar or equal to 0.4. This represents a similar to 25% increase over a time interval of 2 Gyr. (3) There is a marked difference in the morphological content of EDisCS and SDSS clusters. None of the EDisCS clusters have early-type galaxy fractions greater than 0.6 whereas half of the SDSS clusters lie above this value. This difference is seen in clusters of all velocity dispersions. (4) There is a strong and clear correlation between morphology and star formation activity in SDSS and EDisCS clusters in the sense that decreasing fractions of [OII] emitters are tracked by increasing early-type fractions. This correlation holds independent of cluster velocity dispersion and redshift even though the fraction of [OII] emitters decreases from z similar to 0.8 to z similar to 0.06 in all environments. Our results pose an interesting challenge to structural transformation and star formation quenching processes that strongly depend on the global cluster environment (e. g., a dense ICM) and suggest that cluster membership may be of lesser importance than other variables in determining galaxy properties.

We present K-band data for the brightest cluster galaxies (BCGs) from the ESO Distant Cluster Survey (EDisCS). These data are combined with the photometry published by Aragon Salamanca, Baugh & Kauffmann and a low-redshift comparison sample built from the BCG catalogue of von der Linden et al. BCG luminosities are measured inside a metric circular aperture with 37 kpc diameter. In agreement with previous studies, we find that the K-band Hubble diagram for BCGs exhibits very low scatter (similar to 0.35) over a redshift range of 0 < z < 1. The colour and rest-frame K-band luminosity evolution of the BCGs are in good agreement with population synthesis models of stellar populations which formed at z > 2 and evolved passively thereafter. In contrast with some previous studies, we do not detect any significant change in the stellar mass of the BCG since z similar to 1. These results do not seem to depend on the velocity dispersion of the parent cluster. We also find that there is a correlation between the 1D velocity dispersion of the clusters (sigma(cl)) and the K-band luminosity of the BCGs ( after correcting for passive-evolution). The clusters with large velocity dispersions, and therefore masses, tend to have brighter BCGs, i.e. BCGs with larger stellar masses. This dependency, although significant, is relatively weak: the stellar mass of the BCGs changes only by similar to 70 per cent over a two order of magnitude range in cluster mass. Furthermore, this dependency does not change significantly with redshift. We have compared our observational results with the hierarchical galaxy formation and evolution model predictions of De Lucia & Blaizot. We find that the models predict colours which are in reasonable agreement with the observations because the growth in stellar mass is dominated by the accretion of old stars. However, the stellar mass in the model BCGs grows by a factor of 3-4 since z = 1, a growth rate which seems to be ruled out by the observations. The models predict a dependency between the BCG's stellar mass and the velocity dispersion (mass) of the parent cluster in the same sense as the data, but the dependency is significantly stronger than observed. However, one major difficulty in this comparison is that we have measured magnitudes inside a fixed metric aperture while the models compute total luminosities.