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

Abstract: 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.

• The paper presents a final spectroscopic release featuring 35,016 galaxies and AGN up to z~6.7, vastly expanding deep field observations.
• The paper employs multi-slit spectroscopy with VIMOS and a rigorous flagging system to ensure redshift reliability between 83% and 100% across key regimes.
• The paper demonstrates how a magnitude-limited sample can refine galaxy evolution models and inform future cosmological studies.

Overview of the VIMOS VLT Deep Survey Final Data Release

The study at hand delineates the VIMOS VLT Deep Survey (VVDS) and its final release data, comprising a vast spectroscopic sample of 35,016 galaxies and Active Galactic Nuclei (AGN) extending out to redshift approximately 6.7. It is imperative to mention that the galaxies were selected with an i-band magnitude ranging from 17.5 to 24.75, showcasing an exemplary magnitude-limited selection strategy. The aim to amass such extensive samples at diverse epochs is integral in elucidating the galaxy evolution dynamics within the cosmological framework, tracking formation, spatial distribution, and evolutionary trajectories across cosmic epochs.

Data Collection and Processing

The VVDS utilizes the VIsible Multi-Object Spectrograph (VIMOS) on the Very Large Telescope (VLT) equipped with the capability of multi-slit spectroscopy. It operates across different surveys—VVDS-Wide, VVDS-Deep, and VVDS-UltraDeep—each focusing on different redshift and magnitude regimes to capture a comprehensive picture of galaxies across a spectrum of epochs. These surveys achieved a cumulative spectroscopic catalog encompassing 34,594 galaxies, 422 type-I AGNs, as well as a considerable sample of Galactic stars.

A focal point of this work is the robust methodology for assigning spectroscopic redshifts using a reliability flagging system refined via independent observations and reconciliation processes. The reliability spans a commendable 83% to 100% for redshifts flagged between 2 to 4 and 9, ensuring high confidence in the resulting redshift measurements.

Implications and Comparisons

The VVDS stands distinguished by its wide-ranging and depth in redshifts when juxtaposed against other contemporary spectroscopic surveys. Notably, it surpasses peers by a nuanced magnitide curve pushing deeper than comparable projects like the DEEP2 or zCOSMOS surveys, extending the observable frontier to z > 3. Moreover, the extensive area coverage totaling up to 8.7 square degrees empowers a wealth of scientific inquiries into large scale structure formations, as well as insights into the early universe conditions as captured by the Lyman-alpha emitter population identified in high redshift regimes.

Theoretical and Practical Impact

The findings strengthened by high fidelity spectroscopic redshift data hold an essential place in further refining galaxy formation and evolution models. The survey yields key volume-complete samples enriched with spectroscopic success rates, contributing to refinement in cosmological models and enhancing simulations of large scale structure in the Universe. The VVDS further corroborates that integral field spectroscopy rooted in such comprehensive surveys can substantially advance observational cosmology.

Future Directions

The VVDS dataset also stands as a crucial benchmark for future endeavors, potentially enhancing AI applications in automating redshift calculations or employing machine learning techniques to uncover deeper insights into galaxy evolution patterns. Its legacy availability via public datasets will likely foster a plethora of follow-up studies, extending its impact on the domain beyond immediate findings.

In summation, the VVDS proves a seminal enterprise in deep spectroscopic surveys, blending expansive redshift spectra with depth and reliability. The detailed scrutiny of high redshift galaxies it facilitates is invaluable, entrenching its pivotal stance in astrophysical research pursuits and cosmic understanding advancement.