In this paper we present a new deep, wide-field near-infrared imaging survey. Our J- and K-band observations in four separate fields (0226-04, 2217+00, 1003+02, 1400+05) complement optical BVRI, ...ultraviolet and spectroscopic observations undertaken as part of the VIMOS-VLT deep survey (VVDS). In total, our survey spans 6400 arcmin2. Our catalogues are reliable in all fields to at least K 6 20.75 and J 6 21.50 (defined as the magnitude where object contamination is less than 10% and completeness greater than 90%). Taken together these four fields represents a unique combination of depth, wavelength coverage and area. Most importantly, our survey regions span a broad range of right ascension and declination which allow us to make a robust estimate of the effects of cosmic variance. We describe the complete data reduction process from raw observations to the construction of source lists and outline a comprehensive series of tests carried out to characterise the reliability of the final catalogues. From simulations we determine the completeness function of each final stacked image, and estimate the fraction of spurious sources in each magnitude bin. We compare the statistical properties of our catalogues with literature compilations. We find that our J- and K-selected galaxy counts are in good agreement with previously published works, as are our (J - K) versus K colour-magnitude diagrams. Stellar number counts extracted from our fields are consistent with a synthetic model of our galaxy. Using the location of the stellar locus in colour-magnitude space and the measured field-to-field variation in galaxy number counts we demonstrate that the absolute accuracy of our photometric calibration is at the 5% level or better. Finally, an investigation of the angular clustering of K-selected extended sources in our survey displays the expected scaling behaviour with limiting magnitude, with amplitudes in each magnitude bin in broad agreement with literature values. In summary, these catalogues will be an excellent tool to investigate the properties of near-infrared selected galaxies, and such investigations will be the subject of several articles currently in preparation.
VIMOS (Visible Multi‐Object Spectrograph) is a multiobject imaging spectrograph installed at the VLT (Very large Telescope) at the ESO (European Southern Observatory) Paranal Observatory that is ...especially suited for survey work. VIMOS is characterized by its very high multiplexing factor: it is possible to take up to 800 spectra with 10
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long slits in a single exposure. To fully exploit its multiplexing potential, we designed and implemented a dedicated software tool: the VIMOS Mask Preparation Software (VMMPS), which allows the astronomer to select the objects to be spectroscopically observed, and provides for automatic slit positioning and slit number maximization within the instrumental constraints. The output of VMMPS is used to manufacture the slit masks to be mounted in the instrument for spectroscopic observations.
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 Mpc3. 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 Å. 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.
In this paper we describe the U-band imaging of the F02 deep field, one of the fields in the VIRMOS Deep Imaging Survey. The observations were done at the ESO/MPG 2.2 m telescope at La Silla (Chile) ...using the 8k x 8k Wide-Field Imager (WFI). The field is centered at alpha (J2000) = 02 super(h)26 super(m)00 super(s) and delta (J2000) = -04 degree 30'00 double prime , the total covered area is 0.9 deg super(2) and the limiting magnitude (50% completeness) is U sub(AB) similar to 25.4 mag. Reduction steps, including astrometry, photometry and catalogue extraction, are first discussed. The achieved astrometric accuracy (rms) is similar to 0.2 double prime with reference to the I-band catalog and similar to 0.07 double prime internally (estimated from overlapping sources in different exposures). The photometric accuracy including uncertainties from photometric calibration, is <0.1 mag. Various tests are then performed as a quality assessment of the data. They include: (i) the color distribution of stars and galaxies in the field, done together with the BVRI data available from the VIMOS survey; (ii) the comparison with previous published results of U-band magnitude-number counts of galaxies.
Aims. By combining data from the VIMOS VLT Deep Survey (VVDS) with the Spitzer Wide-area InfraRed Extragalactic survey (SWIRE), we have built the currently largest spectroscopic sample of high ...redshift galaxies selected in the rest-frame near-infrared. We have obtained 2040 spectroscopic redshifts of galaxies with (m_) _{\rm AB} < 21.5 at 3.6 \mu m, and 1255 spectroscopic redshifts of galaxies with (m_) _{\rm AB} < 21. These allow us to investigate the clustering evolution of galaxies selected via their rest- frame near-infrared luminosity in the redshift range 0.2 < z < 2.1. Methods. We use the projected two-point correlation function w_{\rm p}(r_{\rm p}) to study the three dimensional clustering properties of galaxies detected at 3.6 \mu m and 4.5 \mu m with the InfraRed Array Camera (IRAC) in the SWIRE survey with measured spectroscopic redshifts from the first epoch VVDS. We compare these properties to those of a larger sample of 16672 SWIRE galaxies for which we have accurate photometric redshifts in the same field. Results. We find that in the 3.6 \mu m and 4.5 \mu m flux limited samples, the apparent correlation length does not change from redshift similar to 2 to the present. The measured correlation lengths have a mean value of r sub(0) \simeq 3.9\pm0.5 h super(-1) Mpc for the galaxies selected at 3.6 \mu m and a mean value of r sub(0) \simeq 4.4\pm0.5 h super(-1) Mpc for the galaxies selected at 4.5 \mu m, across the whole redshift range explored. These values are larger than those typicaly found for I-band selected galaxies at I_{\rm AB} < 24, for which r sub(0) varies from 2.69 h super(-1) Mpc to 3.63 h super(-1) Mpc between z = 0.5 to z = 2.1. We find that the difference in correlation length between I-band and 3.6-4.5 \mu m selected samples decreases with increasing redshift, becoming comparable at z \simeq 1.5. We interpret this as evidence that galaxies with older stellar populations and galaxies actively forming stars reside in comparably over-dense environments at epochs earlier than z \simeq 1.5, supporting the recently reported flattening of the color-density relation at high redshift. The increasing difference in correlation length with cosmic time observed between rest-frame UV-optical and near-infrared selected samples could then be an indication that star formation is gradually shifting to lower density regions with decreasing redshift, while the older, passively evolving galaxies remain in the most over-dense peaks.
With the new generation of spectrographs, integral field spectroscopy is becoming a widely used observational technique. The Integral Field Unit (IFU) of the Visible Multi–Object Spectrograph (VIMOS) ...on the ESO VLT allows sampling of a field as large as
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, covered by 6400 fibers coupled with microlenses. We present here the methods of the data‐processing software that has been developed to extract the astrophysical signal of faint sources from the VIMOS IFU observations. We focus on the treatment of the fiber‐to‐fiber relative transmission and the sky subtraction, and the dedicated tasks we have built to address the peculiarities and unprecedented complexity of the data set. We review the automated process we have developed under the VIPGI data organization and reduction environment (Scodeggio et al.2005), along with the quality control performed to validate the process. The VIPGI IFU data‐processing environment has been available to the scientific community to process VIMOS IFU data since 2003 November.
Aims. The availability of wide angle and deep surveys, both in the optical and the radio band, allows us to explore the evolution of radio sources with optical counterparts up to redshift z˜ 1.1 in ...an unbiased way using large numbers of radio sources and well defined control samples of radio-quiet objects. Methods: We use the 1.4 GHz VIMOS-VLA Deep Survey, the optical VIMOS-VLT Deep Survey and the CFHT Legacy Survey to compare the properties of radio-loud galaxies with respect to the whole population of optical galaxies. The availability of multiband photometry and high quality photometric redshifts allows us to derive rest-frame colors and radio luminosity functions to a limit of a B rest-frame magnitude of M_B=-20. We derive spectrophotometric types, following the classification of Zucca et al. (2006, A&A, 455, 879), in order to have a priori knowledge of the optical evolution of different galaxy classes. Results: Galaxy properties and luminosity functions are estimated up to z˜ 1 for radio-loud and radio-quiet early and late type galaxies. Radio-loud late type galaxies show significantly redder colors than radio-quiet objects of the same class and this is related to the presence of more dust in stronger star forming galaxies. We estimate the optical luminosity functions, stellar masses and star formation rate distributions for radio sources and compare them with those derived for a well defined control sample, finding that the probability of a galaxy to be a radio emitter significantly increases at high values of these parameters. Radio-loud early type galaxies exhibit luminosity evolution in their bivariate radio-optical luminosity function, due to evolution in the radio-optical ratio. The lack of evolution of the mass function of radio-loud early type galaxies means that no new AGN are formed at redshift z<1. In contrast, radio-loud late type objects exhibit a strong evolution, both in luminosity and density, of the radio luminosity function for z>0.7. This evolution is a direct effect of the strong optical evolution of this class and no significant change with redshift in the radio-optical ratio is required. With the knowledge of the radio-optical ratio and the optical and radio luminosity functions for late type galaxies, we show that it is possible to estimate the star formation history of the Universe up to redshift z˜ 1.5, using optical galaxies as tracers of the global radio emission.
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