The VIMOS VLT deep survey^*,**

The ultraviolet galaxy luminosity function and luminosity density at 3 4

¹ Integral Science Data Centre, Ch. d'Écogia 16, 1290 Versoix, Switzerland e-mail: Stephane.Paltani@obs.unige.ch
² Geneva Observatory, University of Geneva, Ch. des Maillettes 51, 1290 Sauverny, Switzerland
³ Laboratoire d'Astrophysique de Marseille, UMR 6110 CNRS-Université de Provence, BP 8, 13376 Marseille Cedex 12, France
⁴ Institute for Astronomy, 2680 Woodlawn Dr., University of Hawaii, Honolulu, Hawaii, 96822
⁵ INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
⁶ IASF-INAF, via Bassini 15, 20133, Milano, Italy
⁷ Laboratoire d'Astrophysique de l'Observatoire Midi-Pyrénées (UMR 5572), 14 avenue E. Belin, 31400 Toulouse, France
⁸ IRA-INAF, via Gobetti 101, 40129 Bologna, Italy
⁹ INAF-Osservatorio Astronomico di Roma, via di Frascati 33, 00040 Monte Porzio Catone, Italy
¹⁰ Max Planck Institut fur Astrophysik, 85741, Garching, Germany
¹¹ Institut d'Astrophysique de Paris, UMR 7095, 98bis Bd. Arago, 75014 Paris, France
¹² School of Physics & Astronomy, University of Nottingham, University Park, Nottingham, NG72RD, UK
¹³ Astrophysical Institute Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
¹⁴ INAF-Osservatorio Astronomico di Brera, via Brera 28, Milan, Italy
¹⁵ Observatoire de Paris, LERMA, 61 avenue de l'Observatoire, 75014 Paris, France
¹⁶ Università di Bologna, Dipartimento di Astronomia, via Ranzani 1, 40127 Bologna, Italy
¹⁷ Centre de Physique Théorique, UMR 6207 CNRS-Université de Provence, 13288 Marseille France
¹⁸ Astronomical Observatory of the Jagiellonian University, ul Orla 171, 30-244 Kraków, Poland
¹⁹ INAF-Osservatorio Astronomico di Capodimonte, via Moiariello 16, 80131 Napoli, Italy
²⁰ Centro de Astrofísica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal
²¹ Universitá di Milano-Bicocca, Dipartimento di Fisica, Piazza delle Scienze 3, 20126 Milano, Italy

Received: 8 August 2006
Accepted: 1 December 2006

Abstract

Aims.We study the luminosity function of the high-redshift galaxy population with redshifts  using a purely I-band magnitude-selected spectroscopic sample obtained in the framework of the VIMOS VLT Deep Survey (VVDS).

Methods.We determine the luminosity function from the VVDS, taking care to add as few assumptions and as simple corrections as possible, and compare our results with those obtained from photometric studies, based on Lyman-break selections or photometric-redshift measurements.

Results.We find that in the redshift range , the VVDS luminosity function is parameterized by  mag^-1 Mpc^-3 and , assuming a slope consistent with most previous studies. While is comparable to previously found values, M^* is significantly brighter by about 0.5 mag at least. Using the conservative slope , we find a luminosity density at 1700 Å  W Mpc^-3 and  W Mpc^-3, comparable to that estimated in other studies.

Conclusions.The unexpectedly large number of very bright galaxies found in the VVDS indicates that the color-selection and photometric-redshift techniques that are generally used to build high-redshift galaxy samples may be affected by a significant fraction of color-measurement failures or by incomplete modelling of the mix of stellar emission, AGN contribution, dust absorption and intergalactic extinction assumed to identify high-redshift galaxies, making pure magnitude selection better able to trace the full population. Because of the difficulty to identify all low-luminosity galaxies in a spectroscopic survey, the luminosity density could still be significantly underestimated. We also find that the relative contribution of the most luminous galaxies compared to the fainter ones is at least twice as large in the VVDS compared to former estimates. Therefore, the VVDS paints a quite different picture of the role of the most actively star-forming galaxies in the history of star formation.