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< z <1.5. We apply a self-consistent reconstruction scheme which includes a complete non-linear description of galaxy biasing and which has been thoroughly tested on realistic mock samples. We find that the variance and skewness of the galaxy distribution evolve over this redshift interval in a way that is remarkably consistent with predictions of first- and second-order perturbation theory. This finding confirms the standard gravitational instability paradigm over nearly 9 Gyr of cosmic time and demonstrates the importance of accounting for the non-linear component of galaxy biasing to consistently reproduce the higher-order moments of the galaxy distribution and their evolution.
We have obtained deep and wide field imaging of the Coma cluster of galaxies with the CFH12K camera at CFHT in the B, V, R and I filters. In this paper, we present the observations, data reduction, ...catalogs and first scientific results. We investigated the quality of our data by internal and external literature comparisons. We also checked the realisation of the observational requirements we set. Our observations cover two partially overlapping areas of 42 × 28 arcmin^2, leading to a total area of 0.72 × 0.82 deg^2. We have produced catalogs of objects that cover a range of more than 10 mag. and are complete at the 90% level at B˜25, V˜24, R˜24 and I˜23.5 for stellar-like objects, and at B˜22, V˜21, R˜20.75 and I˜20.5 for faint low-surface-brightness galaxy-like objects. Magnitudes are in good agreement with published values from R˜16 to R˜25. The photometric uncertainties are of the order of 0.1 mag at R˜20 and of 0.3 mag at R˜25. Astrometry is accurate to 0.5 arcsec and also in good agreement with published data. Our catalog provides a rich dataset that can be mined for years to come to gain new insights into the formation and evolution of the Coma cluster and its galaxy population. As an illustration of the data quality, we examine the bright part of the Colour Magnitude Relation (B-R versus R) derived from the catalog and find that it is in excellent agreement with that derived for galaxies with redshifts in the Coma cluster, and with previous CMRs estimated in the literature.
We have obtained wide field images of the Coma cluster in the B, V, R and I bands with the CFH12K camera at CFHT. To search for large scale diffuse emission, we have applied to these images an ...iterative multiscale wavelet analysis and reconstruction technique which made it possible to model all the sources (stars and galaxies) and subtract them from the original images. We found various concentrations of diffuse emission present in the central zone around the central galaxies NGC 4874 and NGC 4889. We characterize the positions, sizes and colors of these concentrations. Some sources do not seem to have strong star formation, while one probably exhibits spiral-like colors. One possible origin for the star forming diffuse emission sources is that in the region of the two main galaxies NGC 4874 and NGC 4889 spiral galaxies have recently been disrupted and star formation is still active in the dispersed material. We also use the characteristics of the sources of diffuse emission to trace the cluster dynamics. A scenario in which the group around NGC 4874 is moving north is consistent with our data.
The VVDS-Wide survey has been designed with the general aim of tracing the large-scale distribution of galaxies at z~1 on comoving scales reaching ~100Mpc/h, 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 I_AB=22.5, targeting four independent fields with size up to 4 sq.deg. each. The whole survey covers 8.6 sq.deg., here we present the general properties of the current redshift sample. This includes 32734 spectra in the four regions (19977 galaxies, 304 type I AGNs, and 9913 stars), covering a total area of 6.1 sq.deg, with a sampling rate of 22 to 24%. The redshift success rate is above 90% independently of magnitude. It is the currently largest area coverage among redshift surveys reaching z~1. We give the mean N(z) distribution averaged over 6.1 sq.deg. Comparing galaxy densities from the four fields shows that in a redshift bin Deltaz=0.1 at z~1 one still has factor-of-two variations over areas as large as ~0.25 sq.deg. This level of cosmic variance agrees with that obtained by integrating the galaxy two-point correlation function estimated from the F22 field alone, and is also in fairly good statistical agreement with that predicted by the Millennium mocks. The variance estimated over the survey fields shows explicitly how clustering results from deep surveys of even ~1 sq.deg. size should be interpreted with caution. This paper accompanies the public release of the first 18143 redshifts of the VVDS-Wide survey from the 4 sq.deg. contiguous area of the F22 field at RA=22h, publicly available at cencosw.oamp.fr
The VIMOS VLT Deep Survey Pozzetti, L.; Bolzonella, M.; Lamareille, F. ...
Astronomy and astrophysics (Berlin),
11/2007, Letnik:
474, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We present a detailed analysis of the Galaxy Stellar Mass Function (GSMF) of galaxies up to $z=2.5$ as obtained from the VIMOS VLT Deep Survey (VVDS). Our survey offers the possibility to investigate ...the GSMF using two different samples: (1) an optical (I-selected $17.5 <I_{\rm AB}<24$) main spectroscopic sample of about 6500 galaxies over 1750 arcmin2 and (2) a near-IR (K-selected $K_{\rm AB}<22.34~{\rm and}~K_{\rm AB}<22.84$) sample of about 10 200 galaxies, with photometric redshifts accurately calibrated on the VVDS spectroscopic sample, over 610 arcmin2. We apply and compare two different methods to estimate the stellar mass ${\cal M}_{\rm stars}$ from broad-band photometry based on different assumptions about the galaxy star-formation history. We find that the accuracy of the photometric stellar mass is satisfactory overall, and show that the addition of secondary bursts to a continuous star formation history produces systematically higher (up to 40%) stellar masses. We derive the cosmic evolution of the GSMF, the galaxy number density and the stellar mass density in different mass ranges. At low redshift ($z\simeq0.2$) we find a substantial population of low-mass galaxies (<10$^9~M_\odot$) composed of faint blue galaxies ($M_I-M_K \simeq 0.3$). In general the stellar mass function evolves slowly up to $z\sim0.9$ and more rapidly above this redshift, in particular for low mass systems. Conversely, a massive population is present up to $z=2.5$ and has extremely red colours ($M_I-M_K\simeq 0.7$–0.8). We find a decline with redshift of the overall number density of galaxies for all masses ($59\pm5$% for ${\cal M}_{\rm stars} > 10^8~M_\odot$ at $z=1$), and a mild mass-dependent average evolution (“mass-downsizing”). In particular our data are consistent with mild/negligible (${<}30$%) evolution up to $z\sim0.7$ for massive galaxies (${>}6\times10^{10}~M_\odot$). For less massive systems the no-evolution scenario is excluded. Specifically, a large fraction (${\ge}50\%$) of massive galaxies have been assembled and converted most of their gas into stars at $z\sim1$, ruling out “dry mergers” as the major mechanism of their assembly history below $z\simeq1$. This fraction decreases to ${\sim}33\%$ at $z\sim2$. Low-mass systems have decreased continuously in number density (by a factor of up to $4.1\pm0.9$) from the present age to $z=2$, consistent with a prolonged mass assembly also at $z<1$. The evolution of the stellar mass density is relatively slow with redshift, with a decrease of a factor of $2.3\pm0.1$ at $z=1$ and about $4.5\pm0.3$ at $z=2.5$.
The properties of galaxies are known to be affected by their environment, but although galaxies in clusters and groups have been quite thoroughly investigated, little is known presently on galaxies ...belonging to filaments of the cosmic web, and on the properties of the filaments themselves. We investigate here the properties of the rich cluster MACSJ0717.5+3745 and its extended filament, by analyzing the distribution and fractions of intra-cluster light (ICL) in the core of this cluster and by trying to detect intra-filament light (IFL) in the filament. We analyze the galaxy luminosity function (GLF) of the cluster core and of the filament. We also study the orientations of galaxies in the filament to better constrain the filament properties. This work is based on Hubble Space Telescope archive data, both from the Hubble Frontier Fields in the F435W, F606W, F814W, and F105W bands, and from a mosaic of images in the F606W and F814W bands. The spatial distribution of the ICL is determined with our new wavelet-based software, DAWIS. The GLFs are extracted in the F606W and F814W bands, with a statistical subtraction of the background, and fit with Schechter functions. The galaxy orientations in the filaments are estimated with SExtractor after correction for the Point Spread Function. We detect a large amount of ICL in the cluster core, but no IFL in the cosmic filament. The fraction of ICL in the core peaks in the F606W filter before decreasing with wavelength. Though quite noisy, the GLFs in the filament are notably different from those of field galaxies, with a flatter faint end slope and an excess of bright galaxies. We do not detect a significant alignment of the galaxies in the filament region that was analyzed.
We have analyzed the galaxy number density and luminosity density profiles of rich clusters of galaxies from redshifts $z\sim0$ to $z\sim0.5$. We show that the luminosity profile computed with bright ...galaxies $(M_R < -21)$ is significantly cusped in the center of the clusters, whatever the redshift. This is in agreement with the dark matter profiles predicted by numerical simulations. The galaxy number density profile for the bright galaxies is fitted equally well with a core model or a cusped model. In contrast, the luminosity and the galaxy number density profiles of the fainter galaxies are significantly better fitted by a core model. We did not detect any statistically significant different fits when applied to data in the range from $z\sim0$ to $z\sim0.5$. The difference in profile between faint and bright galaxies may be due to the rapid (relative to the age of the universe at $z=0$ versus $z=0.5$) destruction of the faint galaxies by tidal forces and merging events in the denser central regions of the clusters. This process could erase the cusp by turning faint galaxies into diffuse light. In this case, the galaxies (with a cusp visible in the bright galaxy number density and mainly in luminosity profiles) would trace the total mass distribution.
Aims: We use the VVDS-Deep first-epoch data to measure the dependence of galaxy clustering on galaxy stellar mass, at z~0.85. Methods: We measure the projected correlation function wp(rp) for ...sub-samples with 0.510^9 Msun to r0 ~ 4.28 h^-1 Mpc for galaxies more massive than 10^10.5 Msun. At the same time, the slope increases from ~ 1.67 to ~ 2.28. A comparison of the observed wp(rp) to local measurements by the SDSS shows that the evolution is faster for objects less massive than ~10^10.5 Msun. This is interpreted as a higher dependence on redshift of the linear bias b_L for the more massive objects. While for the most massive galaxies b_L decreases from 1.5+/-0.2 at z~0.85 to 1.33+/-0.03 at z~0.15, the less massive population maintains a virtually constant value b_L~1.3. This result is in agreement with a scenario in which more massive galaxies formed at high redshift in the highest peaks of the density field, while less massive objects form at later epochs from the more general population of dark-matter halos.
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