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




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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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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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.