This paper presents the VIMOS VLT Deep Survey around the Chandra Deep Field South (CDFS). We have measured 1599 new redshifts with VIMOS on the European Observatory Very Large Telescope - UT3, in an area 21x21.6arcmin^2^, including 784 redshifts in the Hubble Space Telescope - Advanced Camera for Surveys GOODS area. 30% of all objects with I_AB_=24 have been observed independently of magnitude, indicating that the sample is purely magnitude limited. We have reached an unprecedented completeness level of 84% in terms of the ratio of secure measurements vs. observed objects, while 95% of all objects have a redshift measurement. A total of 1452 galaxies, 139 stars, 8 QSOs have a redshift identification, 141 of these being unsecure measurements. The redshift distribution down to IAB=24 is peaked at a median redshift z=0.73, with a significant high redshift tail extending up to ~4. Several high density peaks in the distribution of galaxies are identified. In particular, the strong peak at z=0.735 contains more than 130 galaxies in a velocity range +/-2000km/s distributed all across the transverse ~20h^-1^Mpc of the survey. We are releasing all redshifts to the community, along with the cross identification with HST-ACS GOODS sources on the CENCOS database environment http://cencosw.oamp.fr .
We present 371 galaxy velocities in the field of the very rich cluster A2125 (z~0.25). These were determined using optical spectroscopy collected over several years from both the WIYN 3.5m telescope and NOAO Mayall 4m telescope. Prior studies at a variety of wavelengths (radio, optical, and X-ray) have indicated that A2125 is a likely cluster-cluster merger, a scenario that we are able to test using our large velocity database. We identified 224 cluster galaxies, which were subjected to a broad range of statistical tests using both positional and velocity information to evaluate the cluster dynamics and substructure. The tests confirmed the presence of substructures within the A2125 system at high significance, demonstrating that A2125 is a complex dynamical system. Comparison of the test results with existing simulations strengthens the merger hypothesis and provides clues about the merger geometry and stage. The merger model for the system can reconcile A2125's low X-ray temperature and luminosity with its apparently high richness and might also explain A2125's high fraction of active galaxies identified in prior radio and optical studies.
Multifiber spectroscopy has been obtained for 335 galaxies in the field of the double cluster A3128/A3125, using the 2dF multifiber positioner on the Anglo-Australian Telescope. When combined with previously published results, a total of 532 objects in the double cluster now have known redshifts. We have also obtained a 20ks Chandra ACIS-I image of the central 16'x16' of A3128 and radio imaging of the cluster with the Molonglo Observatory Synthesis Telescope and the Australia Telescope Compact Array. The spatial/kinematic distribution of redshifts in the field of A3128/A3125, when combined with the Chandra ACIS-I image of A3128, reveals a variety of substructures present in the galaxy distribution and in the hot intracluster medium (ICM).
We investigate the morphology and dynamics of the massive nearby galaxy cluster Abell 1413. Using wide field imaging and spectroscopic data obtained from observations at the Canada-France-Hawaii Telescope and archival SDSS data, we build a sample of more than 250 galaxies covering a region centered on the cluster and extending to its outskirts on large scales.
We report results from a panoramic spectroscopic survey of 955 objects in the field of the rich cluster Cl 0024+1654 (z~0.4), complementing the HST imaging 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 (1334 in Table 2), including 486 cluster members spread across an area 10Mpc 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.
We present 865 redshifts of galaxies located in the equatorial strip -17.5 deg <= Dec. <= -2.5 deg in the right ascension range 20 h <= R.A. <= 5 h. Redshifts have been obtained for the complete sample of all 833 galaxies in the Morphological Catalog of Galaxies with magnitudes brighter than m = 14.5 (corresponding approximately to m(Zwicky) = 15.0). This sample also includes three galaxies from other sources with more reliable magnitudes, satisfying this limit, and 29 fainter galaxies, usually companions of the galaxies in the magnitude limited sample. Our maps of a very large volume of nearby space demonstrate a variety of coherent large scale structures which include large voids, 20-50 h^-1^ Mpc in diameter and large walls at least 70 h^-1^ Mpc across.
We have measured redshifts for 241 galaxies selected from the Zwicky catalog with magnitudes 15.6 or 15.7 in the region (26.5deg<=delta<=32.5deg, 8h<=alpha=<17h). This region is the original CfA "Slice of the Universe", which was complete to 15.5; now nearly all Zwicky-catalog galaxies in the region have measured redshifts. These somewhat fainter galaxies outline the same structures as the brighter ones. By examinating a sample of 27 galaxies within the most prominent void we find (1) the fraction of absorption-line galaxies is typical of regions outside the cores of rich clusters; and (2) the local morphology-density relation holds within the globally underdense void.
Constraints on the mass distribution in high-redshift clusters of galaxies are currently not very strong. We aim to constrain the mass profile, M(r), and dynamical status of the z~0.8 LCDCS 0504 cluster of galaxies that is characterized by prominent giant gravitational arcs near its center. 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.
We use dense redshift surveys of nine galaxy clusters at z~0.2 to compare the galaxy distribution in each system with the projected matter distribution from weak lensing. By combining 2087 new MMT/Hectospec redshifts and the data in the literature, we construct spectroscopic samples within the region of weak-lensing maps of high (70%-89%) and uniform completeness.
