The ESO-Spitzer Imaging extragalactic Survey (ESIS)^{*,**,***,****}

II. VIMOS I, z wide field imaging of ELAIS-S1 and selection of distant massive galaxies

¹ Max-Planck-Institut für Extraterrestrische Physik (MPE), Postfach 1312, 85741 Garching, Germany e-mail: berta@mpe.mpg.de; ste_atreb@yahoo.it
² Dipartimento di Astronomia, Università di Padova, Vicolo dell'Osservatorio 3, 35122 Padova, Italy
³ INAF – Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy
⁴ Joint Astronomy Centre, University Park, 660 N. Aohoku Place, Hilo, HI 96720, USA
⁵ Dipartimento di Astronomia, Università di Bologna, via Ranzani 1, 40127 Bologna, Italy
⁶ INAF – Osservatorio Astronomico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
⁷ Centro de Astronomia & Astrofisica da Universidade de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal
⁸ CEA / Service d'Astrophysique, Bat 709 CE-Saclay, Orme des Merisiers, 91191 Gif-sur-Yvette, France
⁹ Dipartimento di Fisica, Università degli Studi “Roma Tre”, via della Vasca Navale 84, 00146 Roma, Italy
¹⁰ Department of Astronomy, University of Virginia, Charlottesville, VA 22904, USA
¹¹ Infrared Processing & Analysis Center, California Institute of Technology 100-22, Pasadena, CA 91125, USA
¹² INAF – Osservatorio Astronomico di Roma, via Frascati 33, 00044 Monteporzio Catone, Italy
¹³ Astrophysics Group, Blackett Laboratory, Imperial College of Science Technology and Medicine, Prince Consort Road, London SW7 2AZ, UK
¹⁴ INAF – Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy

Received: 25 April 2008
Accepted: 21 June 2008

Abstract

Context. The ESO-Spitzer Imaging extragalactic Survey (ESIS) is the optical follow up of the Spitzer Wide-area Infra-Red Extragalactic survey (SWIRE) in the ELAIS-S1 region of the sky.

Aims. In the era of observational cosmology, the main efforts are focused on the study of galaxy evolution and its environmental dependence. Wide area, multiwavelength, extragalactic surveys are needed in order to probe sufficiently large volumes, minimize cosmic variance and find significant numbers of rare objects.

Methods. We present VIMOS I and z band imaging belonging to the ESIS survey. A total of ~4 deg² was targeted in I and ~1 deg² in z. Accurate data processing includes removal of fringing, and mosaicking of the complex observing pattern. Completeness levels and photometric uncertainties are estimated through simulations. The multi-wavelength data available in the area are exploited to identify high-redshift galaxies, using the IR-peak technique.

Results. More than 300 000 galaxies have been detected in the I band and ~50 000 in the z band. Object coordinates are defined within an uncertainty of ~0.2 arcsec rms, with respect to GSC 2.2. We reach a 90% average completeness at 23.1 and 22.5 mag (Vega) in the I and z bands, respectively. On the basis of IRAC colors, we identify galaxies having the 1.6 μm stellar peak shifted to . The new I, z band data provide reliable constraints to help avoid low-redshift interlopers and reinforce this selection. Roughly 1000 galaxies between are identified over the ESIS ~4 deg², at the SWIRE 5.8 μm depth (25.8 μJy at 3σ). These are the best galaxy candidates to dominate the massive tail ( ) of the  mass function.