STACKED REST-FRAME ULTRAVIOLET SPECTRA OF Ly{alpha}-EMITTING AND CONTINUUM-SELECTED GALAXIES AT 2 < z < 3.5
- Physics and Astronomy Department, Rutgers University, Piscataway, NJ 08854-8019 (United States)
- Department of Astronomy, Oskar Klein Cosmology Centre, Stockholm University, Stolkholm (Sweden)
- Department of Astronomy and Astrophysics, Pontificia Universidad Catolica de Chile, Santiago (Chile)
- Department of Astronomy, Universidad de Concepcion, Concepcion (Chile)
- Observatories of the Carnegie Institution for Science, Pasadena, CA (United States)
- Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States)
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 Extended Chandra Deep Field-South. Among our sample of 81 UV-bright SFGs, 59 have R < 25.5, of which 32 have rest-frame equivalent widths of W{sub Ly{alpha}} > 20 A, the canonical limit to be classified as an Ly{alpha}-emitting galaxy. We divide our data set into subsamples based on properties that 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{sub Ly{alpha}} > 20 A have bluer UV continua, weaker low-ionization interstellar absorption lines, weaker C IV absorption, and stronger Si II* nebular emission than those with W{sub Ly{alpha}} < 20 A. We measure a velocity offset of {Delta}v {approx} 600 km s{sup -1} between Ly{alpha} emission and low-ionization absorption, which does not vary substantially among any of our subsamples. We find that the interstellar component, as opposed to the stellar component, dominates the high-ionization absorption line profiles. We find that 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 Steidel et al. Moreover, our galaxies with bluer UV colors have stronger Ly{alpha} emission, weaker low-ionization absorption, and more prominent nebular emission line profiles. From a redshift of 2.7 < z < 3.5 to 2.0 < z < 2.7, our subsample of galaxies with W{sub Ly{alpha}} < 20 Angstrom-Sign shows no significant evolution in their physical properties or the nature of their outflows. Among our data set, UV-bright galaxies with W{sub Ly{alpha}} > 20 A 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 {approx} 3 than z {approx} 2.
- OSTI ID:
- 22020531
- Journal Information:
- Astrophysical Journal, Vol. 749, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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