2004/03/20 by R. J. Bouwens, G. D. Illingworth, R. I. Thompson +17 · 121 citations
Mathematics · Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics #Cosmic variance #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gamma-ray bursts and supernovae #Geometry #Hubble Deep Field #Hubble Ultra-Deep Field #Luminosity #Luminosity function #Mathematics #Physics #Redshift #Scaling #Star formation #astro-ph
paper · pdf · doi:10.1086/421016
published in The Astrophysical Journal 606(1), L25-L28 (IOP Publishing) · 5 pages, 5 figures, accepted for publication in the Astrophysical Journal Letters, labelling to the left-hand axis of Figure 4 corrected
arxiv created 2004/03/20 · openalex publication_date 2004/04/08 · arxiv updated 2015/09/23 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
We report on the i -dropouts detected in two exceptionally deep Advanced Camera for Surveys fields ( B 435 , V 606 , i 775 , and z 850 with 10 σ limits of 28.8, 29.0, 28.5, and 27.8, respectively) taken in parallel with the Ultra Deep Field Near-Infrared Camera and Multi-Object Spectrometer observations. Using an i - z > 1.4 cut, we find 30 i -dropouts over 21 arcmin 2 down to z 850, AB = 28.1, or 1.4 i -dropouts arcmin -2 , with significant field-to-field variation (as expected from cosmic variance). This extends i -dropout searches some ~0.9 mag further down the luminosity function than was possible in the Great Observatories Origins Deep Survey (GOODS) fields, yielding a ~7 times increase in surface density. An estimate of the size evolution for UV-bright objects is obtained by comparing the composite radial flux profile of the bright i -dropouts ( z 850, AB < 27.2) with scaled versions of the Hubble Deep Field-North and -South U -dropouts. The best fit is found with a (1 + z ) scaling in size (for fixed luminosity), extending lower redshift (1 < z < 5) trends to z ~ 6. Adopting this scaling and the brighter i -dropouts from both GOODS fields, we make incompleteness estimates and construct a z ~ 6 luminosity function (LF) in the rest-frame continuum UV (~1350 Å) over a 3.5 mag baseline, finding a shape consistent with that found at lower redshift. To evaluate the evolution in the LF from z ~ 3.8, we make comparisons against different scalings of a lower redshift B -dropout sample. Although a strong degeneracy is found between luminosity and density evolution, our best-fit model scales as (1 + z ) -2.8 in number and (1 + z ) 0.1 in luminosity, suggesting a rest-frame continuum UV luminosity density at z ~ 6 that is just 0.38 times that at z ~ 3.8. Our inclusion of the size evolution makes the present estimate lower than previous z ~ 6 estimates.