We present observations collected in the CFHTLS-VIPERS region in the ultraviolet with the GALEX satellite (far- and near-ultraviolet channels) and in the near-infrared with the CFHT/WIRCam camera (Ks band) over an area of 22 and 27deg^2^, respectively. The depth of the photometry was optimised to measure the physical properties (e.g., star formation rate, stellar masses) of all the galaxies in the VIPERS spectroscopic survey. The large volume explored by VIPERS will enable a unique investigation of the relationship between the galaxy properties and their environment (density field and cosmic web) at high redshift (0.5<=z<=1.2). In this paper, we present the observations, the data reductions, and the build-up of the multi-colour catalogues. The CFHTLS-T0007 (gri-{chi}^2^) images are used as reference to detect and measure the Ks -band photometry, while the T0007 u*-selected sources are used as priors to perform the GALEX photometry based on a dedicated software (EMphot). Our final sample reaches NUV_AB_~25 (at 5{sigma}) and K_AB_~22 (at 3{sigma}). The large spectroscopic sample (~51,000 spectroscopic redshifts) allows us to highlight the robustness of our star/galaxy separation and the reliability of our photometric redshifts with a typical accuracy of {sigma]_z_<=0:04 and a fraction of catastrophic failures {eta}<=2% down to i~23. We present various tests on the Ks -band completeness and photometric redshift accuracy by comparing our results with existing overlapping deep photometric catalogues. Finally, we discuss the BzK sample of passive and active galaxies at high redshift and the evolution of galaxy morphology in the (NUV-r) vs (r-Ks) diagram at low redshift (z<=0.25) based on the high image quality of the CFHTLS. The images, catalogues, and photometric redshifts for 1.5 million sources (down to NUV<=25 {union} Ks<=22) are released and available at this URL: http://cesam.lam.fr/vipers-mls/.
Characterisation of cosmic voids gives unique information about the large-scale distribution of galaxies, their evolution, and the cosmological model. We identify and characterise cosmic voids in the VIMOS Public Extragalactic Redshift Survey (VIPERS) at redshift 0.55 <z< 0.9. A new void search method is developed based upon the identification of empty spheres that fit between galaxies. The method can be used to characterise the cosmic voids despite the presence of complex survey boundaries and internal gaps. We investigate the impact of systematic observational effects and validate the method against mock catalogues. We measure the void size distribution and the void-galaxy correlation function.
The goal of this paper is twofold. Firstly, we present F-VIPGI, a new version of the VIMOS Interactive Pipeline and Graphical Interface (VIPGI) adapted to handle FORS2 spectroscopic data taken with the standard instrument configuration. Secondly, we investigate the spectro-photometric properties of a sample of galaxies residing in distant X-ray selected galaxy clusters, the optical spectra of which were reduced with this new pipeline.
From photometric observations of ~47000 stars and spectroscopy of ~11000 stars, we describe the first extensive study of the stellar population of the famous Double Cluster, h and {chi} Persei, down to subsolar masses. By analyzing optical spectra and optical/infrared photometry, we constrain the distance moduli (dM), reddening (E(B-V)), and ages for h Persei, {chi} Persei, and the low-density halo population surrounding both cluster cores. With the exception of mass and spatial distribution, the clusters are nearly identical in every measurable way. From these data, we establish the first spectroscopic and photometric membership lists of cluster stars down to early/mid M dwarfs. At minimum, there are ~5000 members within 10' of the cluster centers, while the entire h and {chi} Persei region has at least ~13000 and as many as 20000 members. The Double Cluster contains ~8400M_{sun}_ of stars within 10' of the cluster centers. We estimate a total mass of at least 20000M_{sun}_. We conclude our study by outlining outstanding questions regarding the past and present properties of h and {chi} Persei. From comparing recent work, we compile a list of intrinsic colors and derive a new effective temperature scale for O-M dwarfs, giants, and supergiants.
The Globular Cluster NGC 3201 was monitored for the existence of variable stars with 16.5<V<20 and 0.2days<period<5days. The files v*.dat contain time-series photometry data in V and I for the 14 variables detected in the field of NGC 3201. Only V6 (a blue straggler contact binary) is a member of the cluster. Due to its low-latitude position, interstellar extinction is present across the field of the cluster. The file phot.dat contains VI photometry data on the monitored stars. These data are NOT corrected for extinction. The variables V7, V8, and V9 were discovered during a follow-up observing run with a different telescope and therefore do not lie in the field covered by phot.dat. Variables V1-V9 are contact system eclipsing binaries, V10 is an RR Lyrae, V11 a semi-detached Algol type binary, V12 a detached binary system, and V13 and V14 are unclassified variable systems.
We present results from ground based VLT/FLAMES spectroscopy in combination with HST data for the globular cluster NGC 6388. The aim of this work is to probe whether this massive cluster hosts an intermediate-mass black hole at its center and to compare the results with the expected value predicted by the M-{sigma} scaling relation.
The abundance and spatial distribution of dwarf galaxies are excellent empirical benchmarks against which to test models of structure formation on small scales. The nearby Centaurus group, with its two subgroups centered on Cen A and M 83, stands out as an important alternative to the Local Group for scrutinizing cosmological model predictions in a group of galaxies context. We have obtained deep optical images of three recently discovered M 83 satellite galaxy candidates with the FORS2 instrument mounted on the Very Large Telescope. We aim to confirm their group membership and study their stellar population. Deep V I-band photometry was used to resolve the brightest stars in our targets. Artificial star tests are performed to estimate the completeness and uncertainties of the photometry. The color-magnitude diagrams reveal the red giant branch (RGB) stars, allowing us to use the Sobel edge detection method to measure the magnitude of the RGB tip and thus derive distances and group membership for our targets. The mean metallicity of the dwarf galaxies were further determined by fitting BASTI model isochrones to the mean RGB locus.
We present VI CCD color-magnitude diagrams for the globular cluster M54 and the Sagittarius dwarf galaxy. These are used to derive the following quantities: [Fe/H] = -1.79 +/- 0.08 for M54 and [Fe/H] = -0.52 +/- 0.09 for Sagittarius. We find a metallicity dispersion of +/- 0.16 dex in M54, and we infer the possible existence of a [Fe/H] ~ -1.3 component in Sagittarius, which may have a metallicity dispersion as well. The mean reddening in the direction of M54 is E(B-V) = 0.13 +/- 0.02. The distances to M54 and Sagittarius, determined using their horizontal branch magnitudes, are identical to within the uncertainties of existing RR Lyrae luminosity-abundance relations. This, together with positional and radial velocity arguments, suggests that M54 is physically associated with Sagittarius. We note that M54 is substantially brighter than the globular cluster members of the Fornax dwarf spheroidal galaxy, and that the metal abundance of Sagittarius is quite high for its estimated absolute magnitude.
We derive quantitative star formation histories of the four suspected tidal dwarf galaxies in the M 81 group, Holmberg IX, BK3N, Arp-loop (A0952+69), and Garland, using Hubble Space Telescope/Wide Field Planetary Camera 2 images in F606W and F814W obtained as part of a Snapshot survey of dwarf galaxies in the Local Universe.
We present deep CCD photometry in the VI passbands using the WIYN 3.5m telescope of a field located approximately 20 southeast of the center of M33; this field includes the region studied by Mould & Kristian in 1986ApJ...305..591M. The color-magnitude diagram (CMD) extends to I~25 and shows a prominent red giant branch (RGB), along with significant numbers of asymptotic giant branch and young main-sequence stars.
