[Paper Review] The VIMOS VLT Deep Survey: Public release of 1599 redshifts to IAB<=24 across the Chandra Deep Field South

O. Le Fèvre, G. Vettolani+6 more|ArXiv.org|Mar 26, 2004

Galaxies: Formation, Evolution, PhenomenaPhysics and Astronomy12 references187 citations

TL;DR

This paper presents the public release of 1,599 redshifts for galaxies, stars, and QSOs with $I_{AB} \leq 24$ in the Chandra Deep Field South, obtained via multi-object spectroscopy with VIMOS on the VLT. The survey achieves 88% completeness in redshift measurement, revealing a median redshift of $z = 0.73$ and strong high-density peaks at $z \approx 0.667$ and $z \approx 0.735$, with significant large-scale structure extending over $\sim 16$ Mpc transverse scale.

ABSTRACT

{This paper presents the VIMOS VLT Deep Survey around the Chandra Deep Field South (CDFS). We have measured 1599 new redshifts with VIMOS on the European Observatory Very Large Telescope - UT3, in an area 21x21.6 arcmin^2, including 784 redshifts in the Hubble Space Telescope - Advanced Camera for Surveys GOODS area. 30% of all objects with I_AB=24 have been observed independently of magnitude, indicating that the sample is purely magnitude limited. We have reached an unprecedented completeness level of 88% in terms of the ratio of secure measurements vs. observed objects, while 95% of all objects have a redshift measurement. A total of 1452 galaxies, 139 stars, 8 QSOs have a redshift identification, 141 of these being unsecure measurements. The redshift distribution down to I_AB=24 is peaked at a median redshift z=0.73, with a significant high redshift tail extending up to ~4. Several high density peaks in the distribution of galaxies are identified. In particular, the strong peak at z=0.735 contains more than 130 galaxies in a velocity range +/-2000 km/s distributed all across the transverse ~20 h^-1 Mpc of the survey. We are releasing all redshifts to the community, along with the cross identification with HST-ACS GOODS sources on the CENCOS database environment http://cencosw.oamp.fr.

Motivation & Objective

• To measure redshifts for a magnitude-limited sample of 1,599 objects with $I_{AB} \leq 24$ in the Chandra Deep Field South to study galaxy evolution and large-scale structure.
• To achieve high completeness in redshift measurement, minimizing selection effects and cosmic variance through a multi-pointing survey design.
• To cross-identify VVDS redshifts with Hubble Space Telescope-Advanced Camera for Surveys (HST-ACS) GOODS sources for multi-wavelength analysis.
• To release a high-quality, publicly accessible redshift catalog with associated photometry and spectral data to support cosmological and galaxy evolution studies.

Proposed method

• Conducted multi-object spectroscopy using the VIMOS instrument on the VLT-UT3 telescope with the low-resolution red grism (LRRED), providing spectral resolution $R \sim 220$ over 5500–9500 Å.
• Performed observations across five VIMOS pointings covering $\sim 453$ arcmin², including the full HST-ACS GOODS area, with 1-arcsec wide slits and 10-arcsec slit lengths.
• Applied automated redshift measurement and quality control using galaxy templates and cross-identification with ESO Imaging Survey and HST-ACS catalogs.
• Classified redshift reliability using a 0–4 quality flag system based on feature confidence: 0 = no measurement, 4 = 100% confidence with strong, high-S/N features.
• Calculated k-corrections and absolute magnitudes using rest-frame galaxy templates fitted to broad-band photometry from EIS and GOODS surveys.
• Released the full catalog via the CENCOS database, enabling interactive queries by coordinates, redshift, ID, or quality flag with integrated access to spectra and images.

Experimental results

Research questions

• RQ1 What is the redshift distribution of galaxies with $I_{AB} \leq 24$ in the Chandra Deep Field South, and what are the dominant structures in this distribution?
• RQ2 How complete is the redshift survey in terms of secure measurements, and what is the impact of magnitude selection on sample purity?
• RQ3 What is the spatial extent and morphology of large-scale structures, such as the $z \approx 0.735$ peak, in the surveyed field?
• RQ4 How do the absolute magnitudes and $B-I$ colors of galaxies evolve with redshift in this magnitude-limited sample?
• RQ5 To what extent can the VVDS redshift catalog be cross-identified with HST-ACS GOODS data for multi-wavelength studies?

Key findings

• The survey achieved an unprecedented 88% completeness in secure redshift measurements (flag 3 or 4) among observed targets, with 95% of all objects having a redshift measurement.
• The redshift distribution peaks at a median redshift of $z = 0.73$, with a significant high-redshift tail extending to $z \sim 4$.
• Two major high-density peaks were identified: one at $z \approx 0.667$ with 149 galaxies and another at $z \approx 0.735$ with 116 galaxies, spanning a transverse scale of $\sim 16$ Mpc in a wall-like structure.
• The sample includes 1,452 galaxies, 139 stars, and 8 QSOs, with 141 redshifts classified as uncertain (flags 0–2).
• The absolute magnitude $M_B$ distribution shows a clear evolution trend with redshift, and the $B-I$ color distribution reveals systematic changes consistent with passive evolution or star formation history.
• The public release of the full catalog, including cross-identification with HST-ACS GOODS sources, enables detailed multi-wavelength studies of galaxy evolution and large-scale structure in the early universe.