the UV Continuum of Z > 1 Star-forming Galaxies in the Hubble Ultraviolet Ultradeep Field

Date

2014-09

Authors

Kurczynski, Peter
Gawiser, Eric
Rafelski, Marc
Teplitz, Harry I.
Acquaviva, Viviana
Brown, Thomas M.
Coe, Dan
de Mello, Duilia F.
Finkelstein, Steven L.
Grogin, Norman A.

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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(similar to 0.006L(z=1)(); 0.02L(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 theirmean (median) values (beta)= -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, d beta/dM= -0.11 +/- 0.01, and no evolution in d beta/dM with redshift. A modest increase in dust reddening with redshift and luminosity, Delta E(B -V) similar to 0.1, and a comparable increase in the dispersion of dust reddening atz < 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, d beta/dz=-0.09 +/- 0.01 for low luminosity (0.05 Lz=3), and d beta/dz = -0.06 +/- 0.01 for medium luminosity (0.25 L-z=3()) galaxies.

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Citation

Kurczynski, Peter, Eric Gawiser, Marc Rafelski, Harry I. Teplitz, Viviana Acquaviva, Thomas M. Brown, Dan Coe et al. "The UV Continuum of z> 1 Star-forming Galaxies in the Hubble Ultraviolet UltraDeep Field." The Astrophysical Journal Letters, Vol. 793, No. 1 (Sep., 2014): L5.