We measure the morphology-density relation of galaxies at z = 1 across the full 3 orders of magnitude in projected galaxy density available in low-redshift studies. Our study adopts techniques that are comparable with those applied at lower redshifts, allowing a direct investigation of how the morphological segregation of galaxies has evolved over the last 8 Gyr. Although the morphology-density relation, as described by the fraction of early-type (E+S0) galaxies, was in place at z = 1, its form differs from that observed at both z = 0 and z = 0.5. In the highest density regions the early-type fraction has increased steadily with time from f(E+S0) = 0.7+/-0.1 at z = 1 to f(E+S0) = 0.9+/-0.1 at the present epoch. However, in intermediate-density regions corresponding to groups and the accretion regions of rich clusters, significant evolution appears to begin only after z = 0.5. Finally, at the lowest densities, no evolution is observed for the early-type fraction of field galaxies, which remains constant at f(E+S0) = 0.4+/-0.1 at all epochs. We examine a simple picture consistent with these observations where the early-type population at z = 1 is comprised largely of elliptical galaxies. Subsequent evolution in both intermediate and dense regions is attributed to the transformation of spirals into lenticulars. Further progress in verifying our hypothesis may be achieved through distinguishing ellipticals and lenticulars at these redshifts through resolved dynamical studies of representative systems.

We present observations of 77 early-type galaxies imaged with the PC1 CCD of the Hubble Space Telescope (HST) WFPC2. "Nuker-law'' parametric fits to the surface brightness profiles are used to classify the central structure into "core'' or "power-law'' forms. Core galaxies are typically rounder than power-law galaxies. Nearly all power-law galaxies with central ellipticities epsilon >= 0.3 have stellar disks, implying that disks are present in power-law galaxies with epsilon < 0.3 but are not visible because of unfavorable geometry. A few low-luminosity flattened core galaxies also have disks; these may be transition forms from power-law galaxies to more luminous core galaxies, which lack disks. Several core galaxies have strong isophote twists interior to their break radii, although power-law galaxies have interior twists of similar physical significance when the photometric perturbations implied by the twists are evaluated. Central color gradients are typically consistent with the envelope gradients; core galaxies have somewhat weaker color gradients than power-law galaxies. Nuclei are found in 29% of the core galaxies and 60% of the power-law galaxies. Nuclei are typically bluer than the surrounding galaxy. While some nuclei are associated with active galactic nuclei (AGNs), just as many are not; conversely, not all galaxies known to have a low-level AGN exhibit detectable nuclei in the broadband filters. NGC 4073 and 4382 are found to have central minima in their intrinsic starlight distributions; NGC 4382 resembles the double nucleus of M31. In general, the peak brightness location is coincident with the photocenter of the core to a typical physical scale of < 1 pc. Five galaxies, however, have centers significantly displaced from their surrounding cores; these may be unresolved asymmetric double nuclei. Finally, as noted by previous authors, central dust is visible in about half of the galaxies. The presence and strength of dust correlates with nuclear emission; thus, dust may outline gas that is falling into the central black hole. The prevalence of dust and its morphology suggest that dust clouds form, settle to the center, and disappear repeatedly on similar to 10(8) yr timescales. We discuss the hypothesis that cores are created by the decay of a massive black hole binary formed in a merger. Apart from their brightness profiles, there are no strong differences between core galaxies and power-law galaxies that demand this scenario; however, the rounder shapes of core, their lack of disks, and their reduced color gradients may be consistent with it.

We investigate the effect of a low-level contamination of hot, old, metal-poor starlight on the inferred stellar populations of early-type galaxies in the core of the Coma Cluster. We find that the required correction to the Balmer and metal absorption-line strengths for old, metal-poor stars does not significantly affect the inferred age of the stellar population when the HP strength is large. Intermediate-aged populations are therefore still needed to explain enhanced Balmer-line strengths in early-type galaxies. This gives us increased confidence in our age estimates for these objects. For galaxies with weak Balmer-line strengths corresponding to very old populations (t > 10 Gyr), however, a correction for hot stars may indeed alter the inferred age, as previously suggested. Finally, the inferred metallicity [Z/H] will always be higher after any correction for old, metal-poor starlight than if it were not taken into account, but the enhancement ratios [E/Fe] will strengthen only slightly.

We report results from a panoramic spectroscopic survey of 955 objects in the field of the rich cluster Cl 0024+1654 (z similar or equal to 0.4), complementing the HSTimaging presented in the first paper in this series. Combining with previous work, we compile a catalog of 1394 unique redshifts in the field of this cluster, including 486 cluster members spread across an area 10 Mpc in diameter. Our new spectroscopic sample includes over 200 high-quality spectra of cluster members. We examine the properties of a large sample of 104 cluster early-type galaxies as a function of cluster radius and local density, using them as sensitive tracers of the various physical processes that may be responsible for galaxy evolution. By constructing the fundamental plane of Cl 0024, we infer an evolution in the mean mass-to-light ratio of early-type galaxies with respect to z = 0 of Delta log (M/L-V) = -0.14 +/- 0.02. In the cluster center, we detect a significantly increased scatter in the relationship compared to that seen in local clusters. Moreover, we observe a clear radial trend in the mass-to-light ratios of individual early-type galaxies, with the oldest galaxies located in the cluster core. Galaxies are apparently younger at larger radius, with E+S0 galaxies in the periphery having M/L-V ratios that nearly match values seen in the field at a similar redshift. The strong radial trend is seen even when the sample is restricted to a narrow range in galaxy mass. Independent spectral indicators used in combination reveal an abrupt interaction with the cluster environment that occurs near the virial radius of Cl 0024, revealed by small bursts of star formation in a population of dim early-type galaxies, as well as by enhanced Balmer absorption for a set of larger E+S0 galaxies closer to the cluster core. We construct a simple infall model used to compare the timescales and strengths of the observed interactions in this cluster. We examine the possibility that bursts of star formation are triggered when galaxies suffer shocks as they encounter the intracluster medium, or by the onset of galaxy harassment.

This is the first paper of a series that will present data and scientific results from the WINGS project, a wide- field, multiwavelength imaging and spectroscopic survey of galaxies in 77 nearby clusters. The sample was extracted from the ROSAT catalogs of X- Ray emitting clusters, with constraints on the redshift (0.04 < z < 0.07) and distance from the galactic plane (vertical bar b vertical bar >= 20 deg). The global goal of the WINGS project is the systematic study of the local cosmic variance of the cluster population and of the properties of cluster galaxies as a function of cluster properties and local environment. This data collection will allow the definition of a local, '' zero- point '' reference against which to gauge the cosmic evolution when compared to more distant clusters. The core of the project consists of wide- field optical imaging of the selected clusters in the B and V bands. We have also completed a multifiber, medium- resolution spectroscopic survey for 51 of the clusters in the master sample. The imaging and spectroscopy data were collected using, respectively, the WFC@ INT and WYFFOS@ WHT in the northern hemisphere, and the WFI@ MPG and 2dF@ AAT in the southern hemisphere. In addition, a NIR (J, K) survey of similar to 50 clusters and an H-a + U survey of some 10 clusters are presently ongoing with the WFCAM@ UKIRT and WFC@ INT, respectively, while a very- wide- field optical survey has also been programmed with OmegaCam@ VST. In this paper we briefly outline the global objectives and the main characteristics of the WINGS project. Moreover, the observing strategy and the data reduction of the optical imaging survey (WINGS-OPT) are presented. We have achieved a photometric accuracy of similar to 0.025 mag, reaching completeness to V similar to 23.5. Field size and resolution (FWHM) span the absolute intervals (1.6 - 2.7) Mpc and (0.7 - 1.7) kpc, respectively, depending on the redshift and on the seeing. This allows the planned studies to obtain a valuable description of the local properties of clusters and galaxies in clusters.

We describe preliminary results from an ultra-sensitive, spectroscopic emission-line survey and illustrate the challenges inherent in identifying high-redshift Ly alpha emitters. Our multi-slit windows technique complements other types of emission-line surveys. Narrowband imagine surveys cover large areas of sky but only detect much brighter objects. Longslit spectra taken along cluster caustics yield intrinsically fainter lensed Ly alpha emitters but probe small volumes of space. We have observed the COSMOS deep field and a field at 15 h +00. To a line flux of a few similar to x 10(-18) ergs s(-1) cm(-2), we found 150 emission-line sources (with no detectable continuum) among 4 masks. These candidates are being re-observed with broad spectral coverage to determine the line identity, To date, the interloper to Ly alpha ratio is about 8:1. The sky positions of the Lya candidates generally do not coincide with those of foreground objects in ultra-deep r band or i' images consistent with the presence of a strong Lyman break. (c) 2005 Published by Elsevier B.V.

The Terrestrial Planet Finder Coronagraph (TPF-C) is a deep space mission designed to detect and characterize Earth-like planets around nearby stars. TPF-C will be able to search for signs of life on these planets. TPF-C will use spectroscopy to measure basic properties including the presence of water or oxygen in the atmosphere, powerful signatures in the search for habitable worlds. This capability to characterize planets is what allows TPF-C to transcend other astronomy projects and become an historical endeavor on a par with the discovery voyages of the great navigators.

Black hole ( BH) masses predicted from the M-center dot-sigma relationship conflict with predictions from the M-center dot-L relationship for high-luminosity galaxies, such as brightest cluster galaxies ( BCGs). The M-center dot-L relationship predicts that some BCGs may harbor BHs with M-center dot approaching 10(10) M-circle dot, while the M-center dot-sigma relationship always predicts M-center dot < 3 x 10(9) M-circle dot. We argue that the M-center dot-L relationship is a plausible description for galaxies of high luminosity. If the cores in central stellar density are formed by binary BHs, the inner core cusp radius, r(gamma), may be an independent witness of M-center dot. Using central structural parameters derived from a large sample of early-type galaxies observed by HST, we argue that L is superior to sigma as an indicator of r(gamma). Further, the r(gamma)-M-center dot relationship for 11 core galaxies with measured M-center dot appears to be consistent with the M-center dot-L relationship for BCGs. BCGs have large cores appropriate for their large luminosities that may be difficult to generate with the more modest BH masses inferred from the M-center dot-sigma relationship. M-center dot similar to M would be expected for BCGs, if they were formed in dissipationless mergers, which should preserve the ratio of BH to stellar mass, M. This scenario appears to be consistent with the slow increase in sigma with L and the more rapid increase in effective radii with L seen in BCGs as compared to less luminous galaxies. If BCGs have large BHs commensurate with their luminosities, then the local BH mass function for M-center dot > 3 x 10(9) M-circle dot would be nearly an order of magnitude richer than that inferred from the M-center dot-sigma relationship. The volume density of the most luminous QSOs may favor the M-center dot-L relationship.

Aims. We search for and characterize substructures in the projected distribution of galaxies observed in the wide field CCD images of the 77 nearby clusters of the WIde-field Nearby Galaxy-cluster Survey ( WINGS). This sample is complete in X-ray flux in the redshift range 0.04 < z < 0.07.

Context. The WIde-field Nearby Galaxy-cluster Survey (wings) is a project aiming at the study of the galaxy populations in clusters in the local universe (0.04 < z < 0.07) and the influence of environment on the physical properties of galaxies. This survey provides a high quality set of spectroscopic data for similar to 6000 galaxies in 48 clusters. The study of such a large amount of objects requires automatic tools capable of extracting as much information as possible from the data.