UV-dropout galaxies in the goods-south field from WFC3 Early Release Science observations

N. P. Hathi, R. E. Ryan, S. H. Cohen, H. Yan, R. A. Windhorst, P. J. McCarthy, R. W. O'Connell, A. M. Koekemoer, M. J. Rutkowski, B. Balick, H. E. Bond, D. Calzetti, M. J. Disney, M. A. Dopita, Jay A. Frogel, D. N.B. Hall, J. A. Holtzman, R. A. Kimble, F. Paresce, A. SahaJ. I. Silk, J. T. Trauger, A. R. Walker, B. C. Whitmore, And E.T. Young

Research output: Contribution to journalArticlepeer-review

69 Scopus citations


We combine new high sensitivity ultraviolet (UV) imaging from the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) with existing deep HST/Advanced Camera for Surveys optical images from the Great Observatories Origins Deep Survey (GOODS) program to identify UV-dropouts, which are Lyman break galaxy (LBG) candidates at z ≃ 1-3. These new HST/WFC3 observations were taken over 50 arcmin2 in the GOODS South field as a part of the Early Release Science program. The uniqueness of these new UV data is that they are observed in three UV/optical (WFC3 UVIS) channel filters (F225W, F275W, and F336W), which allows us to identify three different sets of UV-dropout samples. We apply Lyman break dropout selection criteria to identify F225W-, F275W-, and F336W-dropouts, which are z ≃ 1.7, 2.1, and 2.7 LBG candidates, respectively. We use multi-wavelength imaging combined with available spectroscopic and photometric redshifts to carefully access the validity of our UV-dropout candidates. Our results are as follows: (1) these WFC3 UVIS filters are very reliable in selecting LBGs with z ≃ 2.0, which helps to reduce the gap between the well-studied z ≳ 3 and z ∼ 0 regimes; (2) the combined number counts with average redshift z ≃ 2.2 agree very well with the observed change in the surface densities as a function of redshift when compared with the higher redshift LBG samples; and (3) the best-fit Schechter function parameters from the rest-frame UV luminosity functions at three different redshifts fit very well with the evolutionary trend of the characteristic absolute magnitude, M*, and the faint-end slope, a, as a function of redshift. This is the first study to illustrate the usefulness of the WFC3 UVIS channel observations to select z ≃ 3 LBGs. The addition of the new WFC3 on the HST has made it possible to uniformly select LBGs from z ≃ 1 to z ≃ 9 and significantly enhance our understanding of these galaxies using HST sensitivity and resolution.

Original languageEnglish (US)
Pages (from-to)1708-1716
Number of pages9
JournalAstrophysical Journal
Issue number2
StatePublished - Sep 10 2010

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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