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arXiv · 1005.1661

The Evolution of the UV Luminosity Function from z ~ 0.75 to z ~ 2.5 using HST ERS WFC3/UVIS Observations

P. A. Oesch·R. J. Bouwens·C. M. Carollo·G. D. Illingworth·D. Magee·M. Trenti·M. Stiavelli·M. Franx·I. Labbe·P. G. van Dokkum
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Abstract

We present UV luminosity functions (LFs) at 1500 Angstrom derived from the HST Early Release Science WFC3/UVIS data acquired over ~50 arcmin^2 of the GOODS-South field. The LFs are determined over the entire redshift range z=0.75-2.5 using two methods, similar to those used at higher redshifts for Lyman Break Galaxies (LBGs): (1) 13-band UV+optical+NIR photometric redshifts to study galaxies in the range z=0.5-2 in three bins of dz=0.5, and (2) dropout samples in three redshift windows centered at z~1.5, z~1.9, and z~2.5. The characteristic luminosity dims by ~1.5 mag from z=2.5 to z=0.75, consistent with earlier work. However, the other Schechter function parameters, the faint-end slope and the number density, are found to be remarkably constant over the range z=0.75-2.5. Using these LF determinations we find the UV luminosity density to increase by ~1.4 dex according to (1+z)^{2.58+-0.15} from z~0 to its peak at z~2.5. Strikingly, the inferred faint-end slopes for our LFs are all steeper than alpha=-1.5, in agreement with higher-redshift LBG studies. Since the faint-end slope in the local universe is found to be much flatter with alpha~=-1.2, this poses the question as to when and how the expected flattening occurs. Despite relatively large uncertainties, our data suggest alpha~=-1.7 at least down to z~1. These new results from such a shallow early dataset demonstrate very clearly the remarkable potential of WFC3/UVIS for the thorough characterization of galaxy evolution over the full redshift range z~0.5 to z~3.

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P. A. Oesch, R. J. Bouwens, C. M. Carollo, G. D. Illingworth, D. Magee, M. Trenti, M. Stiavelli, M. Franx, I. Labbe, P. G. van Dokkum. 2010-11-30. The Evolution of the UV Luminosity Function from z ~ 0.75 to z ~ 2.5 using HST ERS WFC3/UVIS Observations. https://doi.org/10.1088/2041-8205%2F725%2F2%2Fl150

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