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Le Fevre O.,Aix - Marseille University | Cassata P.,Aix - Marseille University | Cucciati O.,National institute for astrophysics | Garilli B.,Istituto di Astrofisica Spaziale e Fisica Cosmica | And 44 more authors.
Astronomy and Astrophysics | Year: 2013

Context. Deep representative surveys of galaxies at different epochs are needed to make progress in understanding galaxy evolution. Aims. We describe the completed VIMOS VLT Deep Survey and the final data release of 35 016 galaxies and type-I AGN with measured spectroscopic redshifts covering all epochs up to redshift z ∼ 6.7, in areas from 0.142 to 8.7 square degrees, and volumes from 0.5×106 to 2×107 h-3 Mpc 3. Methods. We selected samples of galaxies based solely on their i-band magnitude reaching iAB = 24.75. Spectra were obtained with VIMOS on the ESO-VLT integrating 0.75 h, 4.5 h, and 18 h for the Wide, Deep, and Ultra-Deep nested surveys, respectively. We demonstrate that any "redshift desert" can be crossed successfully using spectra covering 3650 ≤ λ ≤ 9350 A. A total of 1263 galaxies were again observed independently within the VVDS and from the VIPERS and MASSIV surveys. They were used to establish the redshift measurements reliability, to assess completeness in the VVDS sample, and to provide a weighting scheme taking the survey selection function into account. We describe the main properties of the VVDS samples, and the VVDS is compared to other spectroscopic surveys in the literature. Results. In total we have obtained spectroscopic redshifts for 34 594 galaxies, 422 type-I AGN, and 12 430 Galactic stars. The survey enabled identifying galaxies up to very high redshifts with 4669 redshifts in 1 ≤ zspec ≤ 2, 561 in 2 ≤ zspec ≤ 3, and 468 with zspec > 3, and specific populations like Lyman-α emitters were identified out to z = 6.62.We show that the VVDS occupies a unique place in the parameter space defined by area, depth, redshift coverage, and number of spectra. Conclusions. The VIMOS VLT Deep Survey provides a comprehensive survey of the distant universe, covering all epochs since z ∼ 6, or more than 12 Gyr of cosmic time, with a uniform selection, which is the largest such sample to date. A wealth of science results derived from the VVDS have shed new light on the evolution of galaxies and AGN and on their distribution in space over this large cosmic time. The VVDS further demonstrates that large deep spectroscopic redshift surveys over all these epochs in the distant Universe are a key tool to observational cosmology. To enhance the legacy value of the survey, a final public release of the complete VVDS spectroscopic redshift sample is available at http://cesam.lam.fr/vvds. © 2013 ESO. Source


Abbas U.,French National Center for Scientific Research | Abbas U.,National institute for astrophysics | de la Torre S.,French National Center for Scientific Research | de la Torre S.,National institute for astrophysics | And 58 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2010

We model the evolution of the mean galaxy occupation of dark matter haloes over the range 0.1 < z < 1.3, using the data from the VIMOS-VLT Deep Survey. The galaxy projected correlation function wp(rp) was computed for a set of luminosity-limited subsamples and fits to its shape were obtained using two variants of halo occupation distribution (HOD) models. These provide us with a set of best-fitting parameters, from which we obtain the average mass of a halo and average number of galaxies per halo. We find that after accounting for the evolution in luminosity and assuming that we are largely following the same population, the underlying dark matter halo shows a growth in mass with decreasing redshift as expected in a hierarchical structure formation scenario. Using two different HOD models, we see that the halo mass grows by 90 per cent over the redshift interval z = [0.5, 1.0]. This is the first time the evolution in halo mass at high redshifts has been obtained from a single data survey and it follows the simple form seen in N-body simulations with M(z) = M0 e-βz, and β = 1.3 ± 0.30. This provides evidence for a rapid accretion phase of massive haloes having a present-day mass M0 ∼ 1013.5 h-1 M⊙, with a m > 0.1 M0 merger event occurring between redshifts of 0.5 and 1.0. Furthermore, we find that more luminous galaxies are found to occupy more massive haloes irrespective of the redshift. Finally, the average number of galaxies per halo shows little increase from redshift z∼ 1.0 to ∼0.5, with a sharp increase by a factor of ∼3 from z ∼ 0.5 to ∼0.1, likely due to the dynamical friction of subhaloes within their host haloes. © 2010 The Authors. Journal compilation © 2010 RAS. Source


Von Ballmoos P.,Roche Holding AG | Alvarez J.,IEEC CSIC | Barriere N.,Space science Laboratory | Boggs S.,Space science Laboratory | And 18 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

DUAL will study the origin and evolution of the elements and explores new frontiers of physics: extreme energies that drive powerful stellar explosions and accelerate particles to macroscopic energies; extreme densities that modify the laws of physics around the most compact objects known; and extreme fields that influence matter in a way that is unknown on Earth. The variability of these extreme objects requires continuous all-sky coverage, while detailed study demands an improvement in sensitivity over previous technologies by at least an order of magnitude. The DUAL payload is composed of an All-Sky Compton Imager (ASCI), and two optical modules, the Laue-Lens Optic (LLO) and the Coded-Mask Optic (CMO). The ASCI serves dual roles simultaneously, both as an optimal focal-plane sensor for deep observations with the optical modules and as a sensitive true all-sky telescope in its own right for all-sky surveys and monitoring. While the optical modules are located on the main satellite, the All-Sky Compton Imager is situated on a deployable structure at a distance of 30 m from the satellite. This configuration not only permits to maintain the less massive payload at the focal distance, it also greatly reduces the spacecraft-induced detector background, and, above all it provides ASCI with a continuous all-sky exposure. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE). Source


von Ballmoos P.,Roche Holding AG | Alvarez J.,IEEC CSIC | Barriere N.,University of California at Berkeley | Boggs S.,University of California at Berkeley | And 18 more authors.
Experimental Astronomy | Year: 2012

DUAL will study the origin and evolution of the elements and explores new frontiers of physics: extreme energies that drive powerful stellar explosions and accelerate particles to macroscopic energies; extreme densities that modify the laws of physics around the most compact objects known; and extreme fields that influence matter in a way that is unknown on Earth. The variability of these extreme objects requires continuous all-sky coverage, while detailed study demands an improvement in sensitivity over previous technologies by at least an order of magnitude. The DUAL payload is composed of an All-Sky Compton Imager (ASCI), and two optical modules, the Laue-Lens Optic (LLO) and the Coded-Mask Optic (CMO). The ASCI serves dual roles simultaneously, both as an optimal focal-plane sensor for deep observations with the optical modules and as a sensitive true all-sky telescope in its own right for all-sky surveys and monitoring. While the optical modules are located on the main satellite, the All-Sky Compton Imager is situated on a deployable structure at a distance of 30 m from the satellite. This configuration not only permits to maintain the less massive payload at the focal distance, it also greatly reduces the spacecraft-induced detector background, and, above all it provides ASCI with a continuous all-sky exposure. © 2012 Springer Science+Business Media B.V. Source


Cucciati O.,National institute for astrophysics | Cucciati O.,French National Center for Scientific Research | Marinoni C.,French National Center for Scientific Research | Iovino A.,National institute for astrophysics | And 44 more authors.
Astronomy and Astrophysics | Year: 2010

Aims. We present a homogeneous and complete catalogue of optical galaxy groups identified in the purely flux-limited (17.5 ≤ IAB ≤ 24.0) VIMOS-VLT deep redshift Survey (VVDS). Methods. We use mock catalogues extracted from the Millennium Simulation, to correct for potential systematics that might affect the overall distribution as well as the individual properties of the identified systems. Simulated samples allow us to forecast the number and properties of groups that can be potentially found in a survey with VVDS-like selection functions. We use them to correct for the expected incompleteness and, to asses in addition, how well galaxy redshifts trace the line-of-sight velocity dispersion of the underlying mass overdensity. In particular, on these mock catalogues we train the adopted group-finding technique i.e., the Voronoi-Delaunay Method (VDM). The goal is to fine-tune its free parameters, recover in a robust and unbiased way the redshift and velocity dispersion distributions of groups (n(z) and n(?), respectively), and maximize, at the same time, the level of completeness and purity of the group catalogue. Results. We identify 318 VVDS groups with at least 2 members in the range 0.2 ≤ z ≤ 1.0, among which 144 (/30) with at least 3 (/5) members. The sample has an overall completeness of ∼60% and a purity of ∼50%. Nearly 45% of the groups with at least 3 members are still recovered if we run the algorithm with a particular parameter set that maximizes the purity (∼75%) of the resulting catalogue. We use the group sample to explore the redshift evolution of the fraction fb of blue galaxies (U ? B ≤ 1) in the redshift range 0.2 ≤ z ≤ 1. We find that the fraction of blue galaxies is significantly lower in groups than in the global population (i.e. in the whole ensemble of galaxies irrespective of their environment). Both of these quantities increase with redshift, the fraction of blue galaxies in groups exhibiting a marginally significant steeper increase. We also investigate the dependence of f b on group richness: not only we confirm that, at any redshift, the blue fraction decreases in systems with increasing richness, but we find that this result continues to hold towards fainter luminosities. © 2010 ESO. Source

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