The ESO-Spitzer Imaging extragalactic Survey (ESIS)-II. VIMOS I, z wide field imaging of ELAIS-S1 and selection of distant massive galaxies

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 fo cused on the study of galaxy evolution and its environmental dependence. Wide area, multiwavelength, ex tragalactic 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 deg 2 were targeted in I and ∼ 1 deg 2 in z . Accurate data processing includes removal of fringing, an d mosaicking of the complex observing pattern. Completeness levels and photometric uncertainti es are estimated through simulations. The multi-wavelengt h data available in the area are exploited to identify high-re dshift galaxies, using the IR-peak technique. Results. More than 300000 galaxies have been detected in the I band and ∼ 50000 in the z band. Object coordinates are defined within an uncertainty of ∼ 0 . 2 arcsec r.m.s., with respect to GSC 2.2. We reach a 90% averag e completeness at 23.1 and 22.5 mag (Vega) in the I and z bands, respectively. On the basis of IRAC colors, we identifi ed galaxies having the 1.6 mu m stellar peak shifted to z = 1 − 3. The new I, z band data provide reliable constraints to avoid low-redshi ft interlopers and reinforce this selection. Roughly 1000 gal axies between z = 2 − 3 were identified over the ESIS ∼ 4 deg 2 , at the SWIRE 5.8 mu m depth (25.8 mu Jy at 3 sigma ). These are the best galaxy candidates to dominate the massi ve tail ( M > 10 11 M ⊙ ) of the z > 2 mass function