THE UV CONTINUUM OF z > 1 STAR-FORMING GALAXIES IN THE HUBBLE ULTRAVIOLET ULTRADEEP FIELD
We estimate the UV continuum slope, β, for 923 galaxies in the range 1 = – 1.382(– 1.830) ± 0.002 (random) ± 0.1 (systematic). We find comparable scatter in β (standard deviation = 0.43) to local dwarf galaxies and 30% larger scatter than z > 2 galaxies. We study the trends of β with redshift and absolute magnitude for binned sub-samples and find a modest color-magnitude relation, dβ/dM = –0.11 ± 0.01, and no evolution in dβ/dM with redshift. A modest increase in dust reddening with redshift and luminosity, ΔE(B – V) ~ 0.1, and a comparable increase in the dispersion of dust reddening 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, dβ/dz = –0.09 ± 0.01 for low luminosity (0.05 L^(*)_(z=3), and dβ/dz = –0.06 ± 0.01 for medium luminosity (0.25 $L^(*)_(z=3) galaxies.