EDP Sciences
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Volume 440, Number 1, September II 2005
Page(s) 61 - 66
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20034109

A&A 440, 61-66 (2005)
DOI: 10.1051/0004-6361:20034109

FORS spectroscopy of galaxies in the Hubble Deep Field-South

D. Rigopoulou1, 2, W. D. Vacca2, 3, S. Berta4, A. Franceschini4 and H. Aussel5

1  Astrophysics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK
    e-mail: dar@astro.ox.ac.uk
2  Max-Planck-Institut für extraterrestrische Physik (MPE), Postfach 1312, Garching 85741, Germany
3  USRA, NASA Ames Research Center, MS 144-2 Moffett Field, CA 94035-1000, USA
4  Dipartimento di Astronomia, Universita' di Padova, Vicolo dell'Osservatorio 2, 35122 Padova, Italy
5  Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, Hawaii 96822, USA

(Received 24 July 2003 / Accepted 18 December 2004 )

We present low resolution multi-object spectroscopy of an I-band magnitude limited ( $I_{{\rm AB}} \simeq$ 23-23.5) sample of galaxies located in an area centered on the Hubble Deep Field-South (HDFS). The observations were obtained using the Focal Reducer/low dispersion Spectrograph (FORS) on the ESO Very Large Telescope. Thirty-two primary spectroscopic targets in the HST-WFPC2 HDFS were supplemented with galaxies detected in the Infrared Space Observatory's survey of the HDFS and the ESO Imaging Deep Survey to comprise a sample of 100 galaxies for spectroscopic observations. Based on detections of several emission lines, such as [OII]$\lambda$3727, H$_{\beta}$ and [OIII]$\lambda$5007, or of other spectroscopic features, we measured accurate redshifts for 50 objects in the central HDFS and flanking fields. The redshift range of the current sample of galaxies is 0.6-1.2, with a median redshift of 1.13 (at I $\simeq$ 23.5 not corrected for completeness). The sample is dominated by starburst galaxies with only a small fraction of ellipticals (~10%). For the emission line objects, the extinction corrected [OII]$\lambda$3727 line strengths yield estimates of star formation rates in the range 0.5-30 $M_{\odot}$ yr-1. We used the present data to derive the [OII]$\lambda$3727 luminosity function up to redshift of 1.2. When combined with [OII]$\lambda$3727 luminosity densities for the local and high redshift Universe, our results confirm the steep rise in the star formation rate (SFR) to z $\simeq$ 1.3.

Key words: cosmology: observations -- surveys -- galaxies: luminosity function, mass function -- galaxies: starburst

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