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arXiv · 1201.5630

Stacked Rest-Frame UV Spectra of Ly$\alpha$-Emitting and Continuum-Selected Galaxies at 2<z<3.5

Michael Berry·Eric Gawiser·Lucia Guaita·Nelson Padilla·Ezequiel Treister·Guillermo Blanc·Robin Ciardullo·Harold Francke·Caryl Gronwall
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Abstract

We present properties of individual and composite rest-UV spectra of continuum- and narrowband-selected star-forming galaxies (SFGs) at a redshift of 2 20 {\AA}, the canonical limit to be classified as a LAE. We divide our dataset into subsamples based on properties we are able to measure for each individual galaxy: Ly{\alpha} equivalent width, rest-frame UV colors, and redshift. Among our subsample of galaxies with R<25.5, those with rest-frame W_{Ly{\alpha}}>20 {\AA} have bluer UV continua, weaker low-ionization interstellar absorption lines, weaker C IV absorption, and stronger Si II* nebular emission than those with W_{Ly{\alpha}}<20 {\AA}. We measure a typical velocity offset of {\Delta}v~600 km s$^{-1}$ between Ly{\alpha} emission and low-ionization absorption among our subsamples. We find that the interstellar component, as opposed to the stellar component, dominates the high-ionization absorption line profiles. We find the low- and high-ionization Si ionization states have similar kinematic properties, yet the low-ionization absorption is correlated with Ly$\alpha$ emission and the high-ionization absorption is not. These trends are consistent with outflowing neutral gas being in the form of neutral clouds embedded in ionized gas as previously suggested by \cite{Steidel2010}. Moreover, our galaxies with bluer UV colors have stronger Ly{\alpha} emission, weaker low-ionization absorption and more prominent nebular emission line profiles. Among our dataset, UV-bright galaxies with W_{Ly{\alpha}}>20 {\AA} exhibit weaker Ly{\alpha} emission at lower redshifts, although we caution that this could be caused by spectroscopic confirmation of low Ly{\alpha} equivalent width galaxies being harder at z~3 than z~2.

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Michael Berry, Eric Gawiser, Lucia Guaita, Nelson Padilla, Ezequiel Treister, Guillermo Blanc, Robin Ciardullo, Harold Francke, Caryl Gronwall. 2012-01-26. Stacked Rest-Frame UV Spectra of Ly$\alpha$-Emitting and Continuum-Selected Galaxies at 2<z<3.5. https://doi.org/10.1088/0004-637x/749/1/4

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