110 research outputs found
News from z~6-10 galaxy candidates found behind gravitational lensing clusters
We summarise the current status of our project to identify and study z~6-10 galaxies thanks to strong gravitational lensing. Building on the detailed work from Richard et al. (2006), we present results from new follow-up observations (imaging) undertaken with ACS/HST and the Spitzer Space Telescope and compare our results with findings from the Hubble Ultra-Deep Field (UDF). These new observations are in agreement with the high-z nature for the vast majority of the candidates presented in Richard et al. (2006). We also discuss the properties of other optical dropout sources found in our searches and related objects (EROs, sub-mm galaxies,...) from other surveys
The VIRMOS-VLT Deep Survey
The aim of the VIRMOS VLT Deep Survey (VVDS) is to study of the evolution of
galaxies, large scale structures and AGNs from a sample of more than 150,000
galaxies with measured redshifts in the range 0<z<5+. The VVDS will rely on the
VIMOS and NIRMOS wide field multi-object spectrographs, which the VIRMOS
consortium is delivering to ESO. Together, they offer unprecedented multiplex
capability in the wavelength range 0.37-1.8microns, allowing for large surveys
to be carried out. The VVDS has several main aspects: (1) a deep multi-color
imaging survey over 18deg^2 of more than one million galaxies, (2) a "wide"
spectroscopic survey with more than 130,000 redshifts measured for objects
brighter than IAB=22.5 over 18deg^2, (3) a "deep" survey with 50,000 redshifts
measured to IAB=24, (4) ultra-deep" surveys with several thousand redshifts
measured to IAB=25, (5) multi-wavelength observations with the VLA and XMM.Comment: 5 pages including figures; to appear in Proc. of the ESO/ECF/STSCI
"Deep Fields" workshop, Garching Oct 2000, (Publ: Springer
The VIMOS Integral Field Unit: data reduction methods and quality assessment
With new generation spectrographs integral field spectroscopy is becoming a
widely used observational technique. The Integral Field Unit of the VIsible
Multi-Object Spectrograph on the ESO-VLT allows to sample a field as large as
54" x 54" covered by 6400 fibers coupled with micro-lenses. We are presenting
here the methods of the data processing software 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 dataset. 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 is available to the
scientific community to process VIMOS-IFU data since November 2003.Comment: 19 pages, 10 figures and 1 table. Accepted for publication in PAS
The VVDS data reduction pipeline: introducing VIPGI, the VIMOS Interactive Pipeline and Graphical Interface
The VIMOS VLT Deep Survey (VVDS), designed to measure 150,000 galaxy
redshifts, requires a dedicated data reduction and analysis pipeline to process
in a timely fashion the large amount of spectroscopic data being produced. This
requirement has lead to the development of the VIMOS Interactive Pipeline and
Graphical Interface (VIPGI), a new software package designed to simplify to a
very high degree the task of reducing astronomical data obtained with VIMOS,
the imaging spectrograph built by the VIRMOS Consortium for the European
Southern Observatory, and mounted on Unit 3 (Melipal) of the Very Large
Telescope (VLT) at Paranal Observatory (Chile). VIPGI provides the astronomer
with specially designed VIMOS data reduction functions, a VIMOS-centric data
organizer, and dedicated data browsing and plotting tools, that can be used to
verify the quality and accuracy of the various stages of the data reduction
process. The quality and accuracy of the data reduction pipeline are comparable
to those obtained using well known IRAF tasks, but the speed of the data
reduction process is significantly increased, thanks to the large set of
dedicated features. In this paper we discuss the details of the MOS data
reduction pipeline implemented in VIPGI, as applied to the reduction of some
20,000 VVDS spectra, assessing quantitatively the accuracy of the various
reduction steps. We also provide a more general overview of VIPGI capabilities,
a tool that can be used for the reduction of any kind of VIMOS data.Comment: 10 pages, submitted to Astronomy and Astrophysic
Extreme emission-line galaxies out to z1 in zCOSMOS. I. Sample and characterization of global properties
We present a thorough characterization of a large sample of 183 extreme
emission-line galaxies (EELGs) at redshift 0.11 < z < 0.93 selected from the
20k zCOSMOS Bright Survey because of their unusually large emission line
equivalent widths. We use multiwavelength COSMOS photometry, HST-ACS I-band
imaging and optical zCOSMOS spectroscopy to derive the main global properties
of EELGs, such as sizes, masses, SFRs, reliable metallicities from both
"direct" and "strong-line" methods. The EELGs are compact (R_50 ~ 1.3 kpc),
low-mass (log(M*/Msol)~7-10) galaxies forming stars at unusually high specific
SFR (log(sSFR/yr) up to ~ -7) compared to main sequence SFGs of the same
stellar mass and redshift. At UV wavelengths, the EELGs are luminous and show
high surface brightness and include strong Ly emitters, as revealed by
GALEX spectroscopy. We show that zCOSMOS EELGs are high-ionization,
low-metallicity systems, with median 12+log(O/H)=8.16, including a handful of
extremely metal-deficient galaxies (<10% solar). While ~80% of the EELGs show
non-axisymmetric morphologies, including clumpy and tadpole galaxies, we find
that ~29% of them show additional low surface-brightness features, which
strongly suggest recent or ongoing interactions. As star-forming dwarfs in the
local Universe, EELGs are most often found in relative isolation. While only
very few EELGs belong to compact groups, almost one third of them are found in
spectroscopically confirmed loose pairs or triplets. We conclude that EELGs are
galaxies caught in a transient and probably early period of their evolution,
where they are efficiently building-up a significant fraction of their
present-day stellar mass in an ongoing galaxy-wide starburst. Therefore, the
EELGs constitute an ideal benchmark for comparison studies between low- and
high-redshift low-mass star-forming galaxies.Comment: Accepted in A&A. Final replacement to match the version in press. It
includes a minor change in the title and a new figur
The VIMOS VLT Deep Survey final data release: a spectroscopic sample of 35016 galaxies and AGN out to z~6.7 selected with 17.5<=i_{AB}<=24.7
We describe the completed VIMOS VLT Deep Survey, and the final data release
of 35016 galaxies and type-I AGN with measured spectroscopic redshifts up to
redshift z~6.7, in areas 0.142 to 8.7 square degrees, and volumes from 0.5x10^6
to 2x10^7h^-3Mpc^3. We have selected samples of galaxies based solely on their
i-band magnitude reaching i_{AB}=24.75. Spectra have been obtained with VIMOS
on the ESO-VLT, integrating 0.75h, 4.5h and 18h for the Wide, Deep, and
Ultra-Deep nested surveys. A total of 1263 galaxies have been re-observed
independently within the VVDS, and from the VIPERS and MASSIV surveys. They are
used to establish the redshift measurements reliability, to assess
completeness, and to provide a weighting scheme taking into account the survey
selection function. We describe the main properties of the VVDS samples, and
the VVDS is compared to other spectroscopic surveys. In total we have obtained
spectroscopic redshifts for 34594 galaxies, 422 type-I AGN, and 12430 Galactic
stars. The survey has enabled to identify galaxies up to very high redshifts
with 4669 redshifts in 1<=z_{spec}<=2, 561 in 2<=z_{spec}<=3 and 468 with
z_{spec}>3, and specific populations like LAE have been 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. The VVDS
provides a comprehensive survey of the distant universe, covering all epochs
since z, or more than 12 Gyr of cosmic time, with a uniform selection, 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 their
distribution in space, over this large cosmic time. A final public release of
the complete VVDS spectroscopic redshift sample is available at
http://cesam.lam.fr/vvds.Comment: Submitted 30 June 2013, Accepted 22 August 2013. Updated with
published versio
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