Crystal L. Martin, Alice E. Shapley, Alison L. Coil, Katherine A. Kornei, Kevin Bundy, Benjamin J. Weiner, Kai G. Noeske, David Schiminovich
We present Keck/LRIS spectra of over 200 galaxies with well-determined redshifts between 0.4 and 1.4. We combine new measurements of near-ultraviolet, low-ionization absorption lines with previously measured masses, luminosities, colors, and star formation rates to describe the demographics and properties of galactic flows. Among star-forming galaxies with blue colors, we find a net blueshift of the Fe II absorption greater than 200 km/s (100 km/s) towards 2.5% (20%) of the galaxies. The fraction of spectra with blueshifts decreases significantly among galaxies with specific star formation rates less than roughly 0.8 Gyr^{-1} and does not vary significantly with stellar mass, color, or luminosity. The insensitivity of the blueshifted fraction to galaxy properties favors collimated outflows, and in this context we demonstrate how the solid angle of the outflow declines with increasing outflow velocity. We also detect enriched infall towards 3-6% of the galaxies, apparently observed at an optimal viewing angle. At least 3 (1) of the 9 infalling streams have a large cross section and velocities commensurate with an extended disk (satellite galaxy). We explain the strong dependence of the Mg II absorption equivalent width on stellar mass, B-band luminosity, and U-B color by resonance emission partially filling in the intrinsic absorption troughs; emission filling can also explain the significant differences often observed between the shape of the Mg II line profile and the absorption troughs of those Fe II transitions that decay primarily by fluorescence. This study provides a new quantitative understanding of gas flows between galaxies and the circumgalactic medium over a critical period in galaxy evolution.
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http://arxiv.org/abs/1206.5552
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