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VIMOS Public Extragalactic Redshift Survey

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VIMOS Public Extragalactic Redshift Survey
NameVIMOS Public Extragalactic Redshift Survey
AcronymVIPERS
OperatorEuropean Southern Observatory; Institut d'Astrophysique de Paris; Istituto Nazionale di Astrofisica
TelescopeVery Large Telescope
InstrumentVIMOS
Startdate2008
Enddate2014
WavelengthOptical
Area24 square degrees
Objects~90,000 galaxies

VIMOS Public Extragalactic Redshift Survey is a large spectroscopic programme that measured redshifts for tens of thousands of galaxies at intermediate redshift, aiming to trace large-scale structure and galaxy evolution between the local Universe and the high-redshift regime. It combined wide-field imaging selections with multi-object spectroscopy on the Very Large Telescope using the VIMOS instrument to produce uniform catalogues used in cosmology and galaxy formation studies. The survey bridged efforts such as Sloan Digital Sky Survey, DEEP2 Redshift Survey, and zCOSMOS while targeting epochs complementary to 2dF Galaxy Redshift Survey and GAMA.

Overview

VIPERS targeted the redshift range z ~ 0.5–1.2 to sample cosmic epochs when dark energy became dynamically important and when galaxy assembly was active. The survey footprint comprised fields within the Canada–France–Hawaii Telescope Legacy Survey Wide areas, overlapping legacy data from CFHTLS, Spitzer Space Telescope, and XMM-Newton to enable multiwavelength studies. Scientific drivers included measuring the growth rate of structure through redshift-space distortions, constraining cosmological parameters in the spirit of Planck (spacecraft) constraints, and studying environmental effects on galaxy properties akin to work by Hubble Space Telescope programmes.

Survey Design and Instrumentation

The programme exploited the multi-slit capabilities of VIMOS on unit telescopes of the European Southern Observatory's Very Large Telescope array to observe large samples efficiently. Target selection relied on photometric catalogues from CFHTLS using magnitude and color cuts calibrated against spectroscopic samples such as VVDS and DEEP2 Redshift Survey. The survey adopted a sampling strategy informed by lessons from Sloan Digital Sky Survey and 2dF Galaxy Redshift Survey to balance depth and area, mitigating cosmic variance similarly to COSMOS (astronomy project). Observational setup used medium-resolution grisms and slit masks inspired by instrumentation choices from VLT FORS2 and Keck Observatory multi-object spectrographs.

Observations and Data Reduction

Observations occurred in service and visitor modes at Paranal Observatory over multiple semesters, coordinated with observatory staff from European Southern Observatory and institutional teams from Institut d'Astrophysique de Paris, Istituto Nazionale di Astrofisica, and collaborating universities. Raw data reduction followed pipelines analogous to those developed for zCOSMOS and VVDS, including bias subtraction, flat-fielding, wavelength calibration with arc lamps used also by FORS2 (VLT) programmes, and sky subtraction techniques similar to those in DEEP2 Redshift Survey. Redshift measurement combined automated cross-correlation algorithms previously applied in 2dF Galaxy Redshift Survey and manual vetting by experienced redshifters trained in protocols employed by Sloan Digital Sky Survey teams.

Data Products and Catalogues

Released data products included spectroscopic redshift catalogues, quality flags, 1D and 2D spectra, and derived quantities such as stellar masses and star-formation rates using spectral energy distribution fitting approaches comparable to methods used by COSMOS (astronomy project), GALEX, and Spitzer Space Telescope analyses. Public catalogues were distributed following practices of Sloan Digital Sky Survey and zCOSMOS with documentation on target selection, completeness matrices, and angular masks akin to products from GAMA releases. Cross-matched ancillary datasets linked VIPERS entries to imaging from CFHTLS, mid-infrared photometry from Spitzer Space Telescope, and X-ray counterparts from XMM-Newton.

Scientific Results and Contributions

VIPERS produced measurements of the two-point correlation function and redshift-space distortions that constrained the growth rate of cosmic structure, contributing complementary tests to those from Planck (spacecraft) and baryon acoustic oscillation analyses by BOSS. Studies using VIPERS data probed galaxy stellar mass functions and their evolution, building on earlier results from DEEP2 Redshift Survey and zCOSMOS, and explored environmental dependence of galaxy properties in the spirit of research by Hubble Space Telescope teams. The survey enabled investigations into galaxy spectral classes, active galactic nuclei demographics compared with Chandra X-ray Observatory and XMM-Newton identifications, and comparisons of clustering amplitude to predictions from numerical simulations such as those by the Millennium Run and hydrodynamical suites used by Illustris collaborators.

Legacy and Impact

As a middle-redshift, wide-area spectroscopic programme, VIPERS filled a parameter space between large local surveys like Sloan Digital Sky Survey and deep pencil-beam surveys like Hubble Deep Field. Its catalogues have been used to calibrate photometric redshift algorithms employed by surveys such as DES and KiDS, and to inform target selection strategies for future facilities including Euclid (spacecraft) and Vera C. Rubin Observatory. VIPERS results have been incorporated into meta-analyses alongside constraints from Planck (spacecraft), BOSS, and eBOSS to refine models of cosmic acceleration and galaxy formation.

Collaborations and Funding

The programme assembled teams from institutions across Europe, including the Institut d'Astrophysique de Paris, Istituto Nazionale di Astrofisica, European Southern Observatory, and multiple universities tied into consortia similar to those of COSMOS (astronomy project) and Sloan Digital Sky Survey. Funding and operational support came from national agencies analogous to Centre National de la Recherche Scientifique and Agence Nationale de la Recherche in France, Italian funding bodies linked to Istituto Nazionale di Astrofisica, and European frameworks like those supporting European Southern Observatory observing programmes. The collaboration published data releases and methodological papers that remain cited alongside work from DEEP2 Redshift Survey, VVDS, and zCOSMOS.

Category:Galaxy surveys