The rotational velocity of distant galaxies, when interpreted as a size (luminosity) indicator, may be used as a tool to select high redshift standard rods (candles) and probe world models and galaxy ...evolution via the classical angular diameter-redshift or Hubble diagram tests. We implement the proposed testing strategy using a sample of 30 rotators spanning the redshift range 0.2 < z < 1 with high resolution spectra and images obtained by the VIMOS/VLT Deep Redshift Survey (VVDS) and the Great Observatories Origins Deep Survey (GOODs). We show that by applying at the same time the angular diameter-redshift and Hubble diagrams to the same sample of objects (i.e. velocity selected galactic discs) one can derive a characteristic chart, the cosmology-evolution diagram, mapping the relation between global cosmological parameters and local structural parameters of discs such as size and luminosity. This chart allows to put constraints on cosmological parameters when general prior information about discs evolution is available. In particular, by assuming that equally rotating large discs cannot be less luminous at z = 1 than at present (M(z=1) lesssim M(0)), we find that a flat matter dominated cosmology (\Omega_{\rm m}=1) is excluded at a confidence level of 2 sigma and an open cosmology with low mass density (\Omega_{\rm m} sim 0.3) and no dark energy contribution (\Omega_{\Lambda}) is excluded at a confidence level greater than 1 sigma. Inversely, by assuming prior knowledge about the cosmological model, the cosmology- evolution diagram can be used to gain useful insights about the redshift evolution of baryonic discs hosted in dark matter halos of nearly equal masses. In particular, in a Lambda CDM cosmology, we find evidence for a bimodal evolution where the low-mass discs have undergone significant surface brightness evolution over the last 8.5 Gyr, while more massive systems have not. We suggest that this dichotomy can be explained by the epochs at which these two different populations last assembled.
Context: The rate at which galaxies grow via successive mergers is a key element in understanding the main phases of galaxy evolution. Aims: We measure the evolution of the fraction of galaxies in ...pairs and the merging rate since redshift z 1 assuming a (H0 = 70 km s-1 Mpc-1, ΩM = 0.3 and ΩΛ = 0.7) cosmology. Methods: From the VIMOS VLT Deep Survey we use a sample of 6464 galaxies with I_AB ≤ 24 to identify 314 pairs of galaxies, each member with a secure spectroscopic redshift, which are close in both projected separation and in velocity. Results: We estimate that at z 0.9, 10.9 ± 3.2% of galaxies with MB(z) ≤ -18-Qz (Q = 1.11) are in pairs with separations Δ rp ≤ 20 h-1 kpc, Δ v≤ 500 km s-1, and with Δ MB ≤ 1.5, significantly larger than 3.8 ± 1.7% at z 0.5; thus, the pair fraction evolves as (1 + z)m with m = 4.73 ± 2.01. For bright galaxies with MB(z = 0) ≤ -18.77, the pair fraction is higher and its evolution with redshift is flatter with m = 1.50 ± 0.76, a property also observed for galaxies with increasing stellar masses. Early-type pairs (dry mergers) increase their relative fraction from 3% at z 0.9 to 12% at z 0.5. The star formation rate traced by the rest-frame OII EW increases by 26 ± 4% for pairs with the smallest separation rp ≤ 20 h-1 kpc. Following published prescriptions to derive merger timescales, we find that the merger rate of MB(z) ≤ -18-Qz galaxies evolves as N_mg = (4.96 ± 2.07)×10-4×(1 + z)2.20 ± 0.77 mergers Mpc-3 Gyr-1. Conclusions: The merger rate of galaxies with MB(z) ≤ -18-Qz has significantly evolved since z 1 and is strongly dependent on the luminosity or stellar mass of galaxies. The major merger rate increases more rapidly with redshift for galaxies with fainter luminosities or stellar mass, while the evolution of the merger rate for bright or massive galaxies is slower, indicating that the slow evolution reported for the brightest galaxies is not universal. The merger rate is also strongly dependent on the spectral type of galaxies involved. Late-type mergers were more frequent in the past, while early-type mergers are more frequent today, contributing to the rise in the local density of early-type galaxies. About 20% of the stellar mass in present day galaxies with log(M/M{ȯ}) ≥ 9.5 has been accreted through major merging events since z = 1. This indicates that major mergers have contributed significantly to the growth in stellar mass density of bright galaxies over the last half of the life of the Universe. based on observations obtained with the European Southern Observatory Telescopes at the Paranal Observatory, under programs 072.A-0586 and 073.A-0647.
The VVDS-Wide survey has been designed to trace the large-scale distribution of galaxies at z ~ 1 on comoving scales reaching ~100~h-1 Mpc, while providing a good control of cosmic variance over ...areas as large as a few square degrees. This is achieved by measuring redshifts with VIMOS at the ESO VLT to a limiting magnitude IAB = 22.5, targeting four independent fields with sizes of up to 4 deg2 each. We discuss the survey strategy which covers 8.6 deg2 and present the general properties of the current redshift sample. This includes 32 734 spectra in the four regions, covering a total area of 6.1 deg2 with a sampling rate of 22 to 24%. This paper accompanies the public release of the first 18 143 redshifts of the VVDS-Wide survey from the 4 deg2 contiguous area of the F22 field at RA = 22^h. We have devised and tested an objective method to assess the quality of each spectrum, providing a compact figure-of-merit. This is particularly effective in the case of long-lasting spectroscopic surveys with varying observing conditions. Our figure of merit is a measure of the robustness of the redshift measurement and, most importantly, can be used to select galaxies with uniform high-quality spectra to carry out reliable measurements of spectral features. We also use the data available over the four independent regions to directly measure the variance in galaxy counts. We compare it with general predictions from the observed galaxy two-point correlation function at different redshifts and with that measured in mock galaxy surveys built from the Millennium simulation. The purely magnitude-limited VVDS Wide sample includes 19 977 galaxies, 304 type I AGNs, and 9913 stars. The redshift success rate is above 90% independent of magnitude. A cone diagram of the galaxy spatial distribution provides us with the current largest overview of large-scale structure up to z ~ 1, showing a rich texture of over- and under-dense regions. We give the mean N(z) distribution averaged over 6.1 deg2 for a sample limited in magnitude to IAB = 22.5. Comparing galaxy densities from the four fields shows that in a redshift bin Δz = 0.1 at z ~ 1 one still has factor-of-two variations over areas as large as ~ 0.25 deg2. This level of cosmic variance agrees with that obtained by integrating the galaxy two-point correlation function estimated from the F22 field alone. It is also in fairly good statistical agreement with that predicted by the Millennium simulations. The VVDS WIDE survey currently provides the largest area coverage among redshift surveys reaching z ~ 1. The variance estimated over the survey fields shows explicitly how clustering results from deep surveys of even 1 deg2 size should be interpreted with caution. The survey data represent a rich data base to select complete sub-samples of high-quality spectra and to study galaxy ensemble properties and galaxy clustering over unprecedented scales at these redshifts. The redshift catalog of the 4 deg2 F22 field is publicly available at cencosw.oamp.fr.
Aims. We present a continuation of our study about the relation between stellar mass and gas-phase metallicity in the VIMOS VLT Deep Survey (VVDS). In this work we extend the determination of ...metallicities up to redshift ≈1.24 for a sample of 42 star-forming galaxies with a mean redshift value of 0.99. Methods: For a selected sample of emission-line galaxies, we use both diagnostic diagrams and empirical calibrations based on Oii emission lines along with the empirical relation between the intensities of the Oiii and Neiii emission lines and the theoretical ratios between Balmer recombination emission lines to identify star-forming galaxies and to derive their metallicities. We derive stellar masses by fitting the whole spectral energy distribution with a set of stellar population synthesis models. Results: These new methods allow us to extend the mass-metallicity relation to higher redshift. We show that the metallicity determinations are consistent with more established strong-line methods. Taken together this allows us to study the evolution of the mass-metallicity relation up to z ≈ 1.24 with good control of systematic uncertainties. We find an evolution with redshift of the average metallicity of galaxies very similar to those reported in the literature: for a given stellar mass, galaxies at z ~ 1 have, on average, a metallicity ~ 0.3 dex lower than galaxies in the local universe. However we do not see any significant metallicity evolution between redshifts z ~ 0.7 (Paper I) and z ~ 1.0 (this paper). We find also the same flattening of the mass-metallicity relation for the most massive galaxies as reported in Paper I at lower redshifts, but again no apparent evolution of the slope is seen between z ~ 0.7 and z ~ 1.0. Based on data obtained with the European Southern Observatory Very Large Telescope, Paranal, Chile, program 070.A-9007, and on data obtained at the Canada-France-Hawaii Telescope, operated by the CNRS in France, CNRC in Canada and the University of Hawaii.
We use one of the deepest spectroscopic samples of broad-line active galactic nuclei (AGN) currently available, extracted from the VIMOS VLT Deep Survey (VVDS), to compute the $\ion{Mg}{ii}$ and ...$\ion{C}{iv}$ virial-mass estimates of 120 super-massive black holes in the redshift range $1.0<z<1.9$ and $2.6<z<4.3$. We find that the mass-luminosity relation shows considerably enhanced dispersion towards low AGN luminosities ($\log L_\mathrm{bol} \sim 45$). At these luminosities, there is a substantial fraction of black holes accreting far below their Eddington limit ($L_\mathrm{bol}/L_\mathrm{Edd} < 0.1$), in marked contrast to what is generally found for AGN of higher luminosities. We speculate that these may be AGN on the decaying branch of their lightcurves, well past their peak activity. This would agree with recent theoretical predictions of AGN evolution. In the electronic Appendix of this paper we publish an update of the VVDS type-1 AGN sample, including the first and most of the second-epoch observations. This sample contains 298 objects of which 168 are new.
We have reconstructed the three-dimensional density fluctuation maps to z ~ 1.5 using the distribution of galaxies observed in the VVDS-Deep survey. We use this overdensity field to measure the ...evolution of the probability distribution function and its lower-order moments over the redshift interval 0.7
From first epoch observations of the VIMOS VLT Deep Survey (VVDS) we have derived luminosity functions for galaxy samples selected by spectral type out to z =1.5. With the VVDS we are able to ...investigate within the same sample the evolution of the type dependent luminosity function selected in several rest-frame bands over 70% of the age of the Universe. The simple lesssim0.5 mag for early type galaxies to similar to 1 mag for the latest type galaxies, while the slope of the luminosity function of each spectral type is consistent with being redshift-independent. The luminosity function of early type galaxies is consistent with passive evolution up to alpha, and continuum images of the Sculptor Group spiral galaxy NGC 55 obtained with the WFI instrument at the 2.2-m telescope of ESO. We identified 21 new planetary nebula candidates. We constructed the O IIIlambda5007 Planetary Nebula Luminosity Function (PNLF) and determined a most likely distance of 2.30 pm 0.35 Mpc. The distance to NGC 55 is a bit larger than previously determined distances, which means that the Sculptor Group is further away from the Local Group than previously thought. The PNLF distance to NGC 55 is comparable to the PNLF distance of NGC 300 (Soffner et al. 1996, A&A, 306, 9), adding support to the suggestion that these galaxies form a bound pair. There doesn't seem to be a shortage of planetary nebula candidates in this metal poor galaxy.
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