EDP Sciences
Free access
Volume 426, Number 2, November I 2004
Page(s) 455 - 462
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20041015

A&A 426, 455-462 (2004)
DOI: 10.1051/0004-6361:20041015

Assessing the galaxy population out to z ~ 2 using the Hubble Deep Field South

T. Wiegert1, D. F. de Mello1, 2, 3 and C. Horellou1

1  Onsala Space Observatory, Chalmers University of Technology, 439 92 Onsala, Sweden
    e-mail: wiegert@physics.umanitoba.ca
2  Laboratory for Astronomy and Solar Physics, Goddard Space Flight Center, Greenbelt, MD 20771, USA
3  Catholic University of America, Washington, DC 20064, USA

(Received 2 April 2004 / Accepted 7 July 2004)

In this work we use the Hubble Deep Field South (HDF-S) version 2 images to assess the galaxy population out to $z \sim 2$. We have used two methods of templates fitting of the spectral energy distributions to obtain photometric redshifts and classify the objects. The Bayesian photometric redshifts gave better results when compared with 54 spectroscopic redshifts available in the literature. Analysis of the rest-frame colour distribution shows a bimodality out to $
z \sim 1.4$ . We separated our sample in a blue and a red population at B-V=0.29. At low redshifts ( 0.2< z <0.6), ~60% of the galaxies have B-V>0.29 whereas at higher redshifts ~60% of the galaxies are bluer than B-V<0.29. Although in low numbers, a population of early-type galaxies (or heavily obscured low redshift galaxies) is seen out to $z \sim 2$.

Key words: cosmology: observations -- galaxies: evolution -- galaxies: statistics -- galaxies: photometry

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