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تسجيل مستخدم جديدStacked Rest-Frame UV Spectra of Ly$alpha$-Emitting and Continuum-Selected Galaxies at 2<z<3.5
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We present properties of individual and composite rest-UV spectra of continuum- and narrowband-selected star-forming galaxies (SFGs) at a redshift of 2<z<3.5 discovered by the MUSYC collaboration in the ECDF-S. Among our sample of 81 UV-bright SFGs, 59 have R<25.5, of which 32 have rest-frame equivalent widths W_{Ly{alpha}}>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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