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arXiv · 1407.3680

The UV Continuum of z > 1 Star-forming Galaxies in the Hubble Ultraviolet UltraDeep Field

Peter Kurczynski·Eric Gawiser·Marc Rafelski·Harry I. Teplitz·Viviana Acquaviva·Thomas M. Brown·Dan Coe·Duilia F. de Mello·Steven L. Finkelstein·Norman A. Grogin·Anton M. Koekemoer·Kyoung-soo Lee·Claudia Scarlata·Brian D. Siana
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Abstract

We estimate the UV continuum slope, beta, for 923 galaxies in the range 1 < z < 8 in the Hubble Ultradeep Field (HUDF). These data include 460 galaxies at 1 < z < 2 down to an absolute magnitude M_{UV} = -14 (~0.006 L*_{z=1}; 0.02 L*_{z=0}), comparable to dwarf galaxies in the local universe. We combine deep HST/UVIS photometry in F225W, F275W, F336W wavebands (UVUDF) with recent data from HST/WFC3/IR (HUDF12). Galaxies in the range 1 < z < 2 are significantly bluer than local dwarf galaxies. We find their mean (median) values = -1.382 (-1.830) +/- 0.002 (random) +/- 0.1 (systematic). We find comparable scatter in beta (standard deviation = 0.43) to local dwarf galaxies and 30% larger scatter than z > 2 galaxies. We study the trends of beta with redshift and absolute magnitude for binned sub-samples and find a modest color-magnitude relation, dbeta/dM = -0.11 +/- 0.01 and no evolution in dbeta/dM with redshift. A modest increase in dust reddening with redshift and luminosity, Delta E(B-V) ~ 0.1, and a comparable increase in the dispersion of dust reddening at z < 2, appears likely to explain the observed trends. At z > 2, we find trends that are consistent with previous works; combining our data with the literature in the range 1 < z < 8, we find a color evolution with redshift, dbeta/dz = -0.09 +/-0.01 for low luminosity (0.05 L*_{z=3}), and dbeta/dz = -0.06 +/-0.01 for medium luminosity (0.25 L*_{z=3}) galaxies.

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Peter Kurczynski, Eric Gawiser, Marc Rafelski, Harry I. Teplitz, Viviana Acquaviva, Thomas M. Brown, Dan Coe, Duilia F. de Mello, Steven L. Finkelstein, Norman A. Grogin, Anton M. Koekemoer, Kyoung-soo Lee, Claudia Scarlata, Brian D. Siana. 2014-07-14. The UV Continuum of z > 1 Star-forming Galaxies in the Hubble Ultraviolet UltraDeep Field. https://doi.org/10.1088/2041-8205/793/1/l5

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