Measuring the build-up of stellar mass is one of the main objectives of studies of galaxy evolution. Traditionally, the mass in stars and the star formation rates have been measured by different ...indicators, such as photometric colours, emission lines, and the UV and IR emission. We intend to show that it is possible to derive the physical parameters of galaxies from their broad-band spectral energy distribution out to a redshift of 1.2. This method has the potential to yield the physical parameters of all galaxies in a single field in a homogeneous way, thus overcoming problems with the sample size that particularly plague methods relying on spectroscopy. We use an extensive dataset, assembled in the context of the VVDS survey, which reaches from the UV to the IR and covers a sample of 84 073 galaxies over an area of 0.89 deg2. We also use a library of 100 000 model galaxies with a wide variety of star formation histories (in particular including late bursts of star formation). We find that we can determine the physical parameters stellar mass, age, and star formation rate with good confidence. We validate the star formation rate determination in particular by comparing it to a sample of spectroscopically observed galaxies with an emission-line measurement. While the attenuation in the galaxies shows more scatter, the mean over the sample is unbiased. Metallicity, however, cannot be measured from rest-frame optical photometry alone. As a first application we use our sample to build the number density function of galaxies as a function of stellar mass, specific star formation rate, and redshift. We are then able to study whether the stellar mass function at a later time can be predicted from the stellar mass function and star formation rate distribution at an earlier time. We find that, between redshifts of 1.02 and 0.47, the predicted growth in stellar mass from star formation agrees with the observed one. However, the predicted stellar mass density for massive galaxies is lower than observed, while the mass density of intermediate mass galaxies is overpredicted. This apparent discrepancy can be explained by major and minor mergers. Indeed, when comparing with a direct measurement of the major merger rate from the VVDS survey, we find that major mergers can account for about half of the mass build-up at the massive end. Minor mergers are very likely to contribute the missing fraction.
We present the first measurements of the Probability Distribution Function (PDF) of galaxy fluctuations in the four-passes, first-epoch VIMOS-VLT Deep Survey (VVDS) cone, covering 0.4x0.4 deg between ...0.4 < z < 1.5. We show that the PDF of density contrasts of the VVDS galaxies is an unbiased tracer of the underlying parent distribution up to redshift z = 1.5, on scales R = 8 and 10 h-1 Mpc. The second moment of the PDF, i.e., the rms fluctuations of the galaxy density field, is to a good approximation constant over the full redshift baseline investigated: we find that, in redshift space, s8 for galaxies brighter than McB = -20 + 5 log h has a mean value of 0.94 c 0.07 in the redshift interval 0.7 < z < 1.5. The third moment, i.e., the skewness, increases with cosmic time: we find that the probability of having underdense regions is greater at z 6 0.7 than it was at z 6 1.5. By comparing the PDF of galaxy density contrasts with the theoretically predicted PDF of mass fluctuations we infer the redshift-, density- and scale-dependence of the biasing function b(z,d,R) between galaxy and matter overdensities up to redshift z = 1.5. Our results can be summarized as follows: i) the galaxy bias is an increasing function of redshift: evolution is marginal up to z 6 0.8 and more pronounced for z QQQ ? 0.8; ii) the formation of bright galaxies is inhibited below a characteristic mass-overdensity threshold whose amplitude increases with redshift and luminosity; iii) the biasing function is non linear in all the redshift bins investigated with non-linear effects of the order of a few to 610% on scales > 5 h-1 Mpc. By subdividing the sample according to galaxy luminosity and colors, we also show that: iv) brighter galaxies are more strongly biased than less luminous ones at every redshift and the dependence of biasing on luminosity at z 6 0.8 is in good agreement with what is observed in the local Universe; v) red objects are systematically more biased than blue objects at all cosmic epochs investigated, but the relative bias between red and blue objects is constant as a function of redshift in the interval 0.7 < z < 1.5, and its value (brel 6 1.4) is similar to what is found at z 6 0.
Context.The VIMOS VLT Deep Survey (VVDS) was undertaken to map the evolution of galaxies, large scale structures, and active galaxy nuclei from the redshift spectroscopic measurements of ~105 objects ...down to an apparent magnitude $I_{AB} = 24$, in combination with a multi-wavelength acquisition for radio, infrared, optical, ultraviolet, and X-rays data. Aims.We present the evolution of the comoving star formation rate (SFR) density in the redshift range $0 < z < 5$ using the first epoch data release of the VVDS, that is 11564 spectra over 2200 arcmin2 in two fields of view, the VVDS-0226-04 and the VVDS-CDFS-0332-27, and the cosmological parameters ($\Omega_\mathrm{M}$, $\Omega_{\Lambda}$, $h)=(0.3$, 0.7, 0.7). Methods.We study the multi-wavelength non dust-corrected luminosity densities at $0 < z < 2$ from the rest-frame far ultraviolet to the optical passbands, and the rest-frame 1500 Å luminosity functions and densities at $2.7 < z < 5$. Results.They evolve from $z=1.2$ to $z=0.05$ according to $(1+z)^{x}$ with $x = 2.05, 1.94, 1.92, 1.14, 0.73, 0.42$, and 0.30 in the FUV-1500, NUV-2800, U-3600, B-4400, V-5500, R-6500, and I-7900 passbands, respectively. From $z=1.2$ to $z=0.2$ the B-band density for the irregular-like galaxies decreases markedly by a factor 3.5 while it increases by a factor 1.7 for the elliptical-like galaxies. We identify several SFR periods; from $z=5$ to 3.4 the FUV-band density increases by at most 0.5 dex, from $z=3.4$ to 1.2 it decreases by 0.08 dex, from $z=1.2$ to $z=0.05$ it declines steadily by 0.6 dex. For the most luminous $M_{AB}(1500~\AA)<-21$ galaxies the FUV-band density drops by 2 dex from $z=3.9$ to $z=1.2$, and for the intermediate $-21<M_{AB}(1500~\AA)<-20$ galaxies it drops by 2 dex from $z=0.2$ to $z=0$. Comparing with dust corrected surveys, at $0.4 \la z \la 2$ the FUV seems obscured by a constant factor of ${\sim}1.8$–2 mag, while at $z<0.5$ it seems progressively less obscured by up to ${\sim}0.9$–1 mag when the dust-deficient early-type population is increasingly dominating the B-band density. Conclusions.The VVDS results agree with a downsizing picture where the most luminous sources cease to efficiently produce new stars 12 Gyrs ago (at $z\simeq 4$), while intermediate luminosity sources keep producing stars until 2.5 Gyrs ago (at $z\simeq 0.2$). A modest contribution of dry mergers and morphologies evolving towards early-type galaxies might contribute to increase the number density of the bright early types at $z<1.5$. Our observed SFR density is not in agreement with a continuous smooth decrease since $z\sim4$.
Aims. In this paper we discuss the mix of star-forming and passive galaxies up to z similar to 2, based on the first epoch VIMOS-VLT Deep Survey (VVDS) data. Methods. We compute rest-frame magnitudes ...and colors and analyse the color-magnitude relation and the color distributions. We also use the multi-band VVDS photometric data and spectral templates fitting to derive multi-color galaxy types. Using our spectroscopic dataset we separate galaxies based on a star-formation activity indicator derived combining the equivalent width of the OII emission line and the strength of the D sub( )n(4000) continuum break. Results. In agreement with previous works we find that the global galaxy rest-frame color distribution follows a bimodal distribution at z \le 1, and we establish that this bimodality holds up to at least z =1.5. The details of the rest-frame color distribution depend however on redshift and on galaxy luminosity, with faint galaxies being bluer than the luminous ones over the whole redshift range covered by our data, and with galaxies becoming bluer as redshift increases. This latter blueing trend does not depend, to a first approximation, on galaxy luminosity. The comparison between the spectral classification and the rest-frame colors shows that about 35-40% of the red objects are in fact star forming galaxies. Hence we conclude that the red sequence cannot be used to effectively isolate a sample of purely passively evolving objects within a cosmological survey. We show how multi-color galaxy types have a slightly higher efficiency than rest-frame color in isolating the passive, non star- forming galaxies within the VVDS sample. Connected to these results is also the finding that the color-magnitude relations derived for the color and for the spectroscopically selected early-type galaxies have remarkably similar properties, with the contaminating star-forming galaxies within the red sequence objects introducing no significant offset in the rest frame colors. Therefore the average color of the red objects does not appear to be a very sensitive indicator for measuring the evolution of the early-type galaxy population.
We measure the evolution of clustering for galaxies with different spectral types from 6495 galaxies with 17.5 less than or equal to I sub(AB) less than or equal to 24 and measured spectroscopic ...redshifts in the first epoch VIMOS-VLT Deep Survey (VVDS). We divide our sample into four classes, based on the fit of well-defined galaxy spectral energy distributions on observed multi-color data. We measure the projected correlation function w sub(p)(r sub(p)) and estimate the best-fit parameters for a power-law real-space correlation function xi (r) = (r/r sub(o)) super(- gamma ). We find the clustering of early-spectral-type galaxies to be markedly stronger than that of late-type galaxies at all redshifts up to z 1.2. At z similar to 0.8, early-type galaxies display a correlation length r sub(0) = 4.8 plus or minus 0.9 h super(-1) Mpc, while late types have r sub(0) = 2.5 plus or minus 0.4 h super(-1) Mpc. For the latest class of star-forming blue galaxies, we are able to push our clustering measurement to an effective redshift z similar to 1.4, for luminous galaxies (M sub(B)(AB) -21). The clustering of these objects increases up to r sub(0) = 3.42 plus or minus 0.7 h super(-1) Mpc for z = 1.2,2.0. The relative bias between early- and late-type galaxies within our magnitude-limited survey remains approximately constant with b = 1.6 plus or minus 0.3 from z = 0 to z = 1.2. This result is in agrement with the local findings and fairly robust against different way of classifying red and blue galaxies. When compared to the expected linear growth of mass fluctuations, a natural interpretation of these observations is that: (a) the assembly of massive early type galaxies is already mostly complete in the densest dark matter halos at z 1; (b) luminous late-type galaxies are located in higher-density, more clustered regions of the Universe at z 1.5 than their local low luminous counterpart, indicating that star formation activity is progressively increasing, going back in time, in the higher-density peaks that today are mostly dominated by old galaxies.
Aims.We have computed the evolution of the rest-frame B-band luminosity function (LF) for bulge and disk-dominated galaxies since z=1.2. Methods: .We use a sample of 605 spectroscopic redshifts with ...IAB? 24 in the Chandra Deep Field South from the VIMOS-VLT Deep Survey, 3555 galaxies with photometric redshifts from the COMBO-17 multi-color data, coupled with multi-color HST/ACS images from the Great Observatories Origin Deep Survey. We split the sample in bulge- and disk-dominated populations on the basis of asymmetry and concentration parameters measured in the rest-frame B-band. Results: .We find that at z=0.4-0.8, the LF slope is significantly steeper for the disk-dominated population (?=-1.19 ± 0.07) compared to the bulge-dominated population (?=-0.53 ± 0.13). The LF of the bulge-dominated population is composed of two distinct populations separated in rest-frame color: 68% of red (B-I)AB>0.9 and bright galaxies showing a strongly decreasing LF slope ?=+0.55 ± 0.21, and 32% of blue (B-I)AB<0.9 and more compact galaxies which populate the LF faint-end. We observe that red bulge-dominated galaxies are already well in place at z?1, but the volume density of this population is increasing by a factor 2.7 between z? 1 and z? 0.6. It may be related to the building-up of massive elliptical galaxies in the hierarchical scenario. In addition, we observe that the blue bulge-dominated population is dimming by 0.7 mag between z? 1 and z? 0.6. Galaxies in this faint and more compact population could possibly be the progenitors of the local dwarf spheroidal galaxies.
This paper presents the evolution of the clustering of the main population of galaxies from z 2 to z = 0.2, from the first epoch VIMOS VLT Deep Survey (VVDS), a magnitude limited sample with 17.5 ...less than or equal to I sub(AB) less than or equal to 24. The sample allows a direct estimate of evolution from within the same survey over the time base sampled. We have computed the correlation functions xi (r sub(p), pi ) and w sub(p)(r sub(p)), and the correlation length r sub(0)(z), for the VVDS-02h and VVDS-CDFS fields, for a total of 7155 galaxies in a 0.61 deg super(2) area. We find that the correlation length in this sample slightly increases from z = 0.5 to z = 1.1, with r sub(0)(z) = 2.2-2.9 h super(-1) Mpc (comoving), for galaxies comparable in luminosity to the local 2dFGRS and SDSS samples, indicating that the amplitude of the correlation function was 2.5 times lower at z 1 than observed locally. The correlation length in our lowest redshift bin z = 0.2, 0.5 is r sub(0) = 2.2 h super(-1) Mpc, lower than for any other population at the same redshift, indicating the low clustering of very low luminosity galaxies, 1.5 mag fainter than in the 2dFGRS or SDSS. The correlation length increases to r sub(0) similar to 3.6 h super(-1) Mpc at higher redshifts z = 1.3, 2.1, as we are observing increasingly brighter galaxies, comparable to galaxies with M sub(BsubAB) = -20.5 locally. We compare our measurement to the DEEP2 measurements in the range z = 0.7, 1.35 and find comparable results when applying the same magnitude and color selection criteria as in their survey. The slowly varying clustering of VVDS galaxies as redshift increases is markedly different from the predicted evolution of the clustering of dark matter, indicating that bright galaxies traced higher density peaks when the large scale structures were emerging from the dark matter distribution 9-10 billion years ago, being supporting evidence for a strong evolution of the galaxy vs. dark matter bias.
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 Mg II and C IV ...virial-mass estimates of 120 super-massive black holes in the redshift range 1.0
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.
We investigate the dependence of galaxy clustering on the galaxy intrinsic luminosity at high redshift, using the data from the First Epoch VIMOS-VLT Deep Survey (VVDS). The size (6530 galaxies) and ...depth (I sub(AB) < 24) of the survey allows us to measure the projected two-point correlation function of galaxies, omega sub(p)(r sub(p)), for a set of volume-limited samples up to an effective redshift < z > = 0.9 and median absolute magnitude -19.6 < M sub(B) < -21.3. Fitting omega sub(p)(r sub(p)) with a single power-law model for the real-space correlation function xi (r) = (r/r sub(0)) super(- gamma ), we measure the relationship of the correlation length r sub(0) and the slope gamma with the sample median luminosity for the first time at such high redshift. Values from our lower-redshift samples (0.1 < z < 0.5) are fully consistent with the trend observed by larger local surveys. In our high redshift sample (0.5 < z < 1.2), we find that the clustering strength suddenly rises around M* sub(B), apparently with a sharper inflection than at low redshifts. Galaxies in the faintest sample (< M sub(B) > = -19.6) have a correlation length r sub(0) = 2.7 super(+) sub(-) super(0) sub(0) super(.) sub(.) super(3) sub(3) h super(-1) Mpc, compared to r sub(0) = 5.0 super(+) sub(-) super(1) sub(1) super(.) sub(.) super(5) sub(6) h super(-1) Mpc at < M sub(B) > = -21.3. The slope of the correlation function is observed to correspondingly steepen significantly from gamma = 1.6 super(+) sub(-) super(0) sub(0) super(.) sub(.) super(1) sub(1) to gamma = 2.4 super(+) sub(-) super(0) sub(0) super(.) sub(.) super(4) sub(2). This is not observed either by large local surveys or in our lower-redshift samples and seems to imply a significant change in the way luminous galaxies trace dark-matter halos at z similar to 1 with respect to z similar to 0. At our effective median redshift z 0.9 this corresponds to a strong difference of the relative bias, from b/b* < 0.7 for galaxies with L < L* to b/b* 1.4 for galaxies with L > L*.
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