The great observatories origins deep survey

A&A 454, 423-435 (2006)
DOI: 10.1051/0004-6361:20054796

VLT/FORS2 spectroscopy in the GOODS-South Field: Part II

E. Vanzella¹, S. Cristiani¹, M. Dickinson², H. Kuntschner³, M. Nonino¹, A. Rettura^{4, 5}, P. Rosati⁴, J. Vernet⁴, C. Cesarsky⁴, H. C. Ferguson⁶, R. A. E. Fosbury³, M. Giavalisco⁶, A. Grazian⁷, J. Haase³, L. A. Moustakas⁸, P. Popesso⁴, A. Renzini⁹, D. Stern⁸ and the GOODS Team

¹ INAF - Osservatorio Astronomico di Trieste, via G.B. Tiepolo 11, 40131 Trieste, Italy
e-mail: vanzella@oats.inaf.it
² National Optical Astronomy Obs., PO Box 26732, Tucson, AZ 85726, USA
³ ST-ECF, Karl-Schwarzschild Str. 2, 85748 Garching, Germany
⁴ European Southern Observatory, Karl-Schwarzschild-Strasse 2, Garching 85748, Germany
⁵ Université Paris-Sud 11, Rue Georges Clemenceau 15, 91405 Orsay, France
⁶ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
⁷ INAF - Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monteporzio Roma, Italy
⁸ Jet Propulsion Laboratory, California Institute of Technology, MS 169-506, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
⁹ INAF - Astronomical Observatory of Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy

(Received 31 December 2005 / Accepted 4 April 2006 )

Abstract
Aims.We present the second campaign of the ESO/GOODS program of spectroscopy of faint galaxies in the GOODS-South field.
Methods.Objects were selected as candidates for VLT/FORS2 observations primarily based on the expectation that the detection and measurement of their spectral features would benefit from the high throughput and spectral resolution of FORS2. The reliability of the redshift estimates is assessed using the redshift-magnitude and color-redshift diagrams and comparing the results with public data.
Results.807 spectra of 652 individual targets have been obtained in service mode with the FORS2 spectrograph at the ESO/VLT, providing 501 redshift determinations. The typical redshift uncertainty is estimated to be $\sigma_z \simeq 0.001$ . Galaxies have been selected adopting three different color criteria and using the photometric redshifts. The resulting redshift distribution typically spans two redshift domains: from z=0.5 to 2 and z=3.5 to 6.2. In particular, 94 B₄₃₅-, V₆₀₆-, i₇₇₅-"dropout" Lyman break galaxies have been observed, yielding redshifts for 65 objects in the interval 3.4<z<6.2. Three sources have been serendipitously discovered in the redshift interval 4.8<z<5.5. Together with the previous release, 930 sources have now been observed and 724 redshift determinations have been carried out. The reduced spectra and the derived redshifts are released to the community through the ESO web page http://www.eso.org/science/goods/. Large scale structures are clearly detected at $z \simeq 0.666, 0.734, 1.096, 1.221, 1.300$ , and 1.614. A sample of 34 sources with tilted [O II]3727 emission has been identified, 32 of them in the redshift range 0.9<z <1.5.

Key words: cosmology: observations -- cosmology: large scale structure of Universe -- Galaxy: general