The Lyα properties of faint galaxies at z ∼ 2-3 with systemic redshifts and velocity dispersions from Keck-MOSFIRE
- Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin Milwaukee, 1900 East Kenwood Boulevard, Milwaukee, WI 53211 (United States)
- Cahill Center for Astrophysics, California Institute of Technology, 1216 East California Boulevard, MS 249-17, Pasadena, CA 91125 (United States)
- Astronomical Observatory, Volgina 7, 11060 Belgrade (Serbia)
- Department of Physics and Astronomy, University of California, Los Angeles, 430 Portola Plaza, Los Angeles, CA 90095 (United States)
- NASA Ames Research Center, Bldg. 211, Room 112, Moffett Field, CA 94035-1000 (United States)
- Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, Ontario M5S 3H4 (Canada)
- Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)
- Department of Physics and Astronomy, University of California, Riverside, 900 University Avenue, Riverside, CA 92521 (United States)
- Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom)
We study the Lyα profiles of 36 spectroscopically detected Lyα-emitters (LAEs) at z ∼ 2-3, using Keck MOSFIRE to measure systemic redshifts and velocity dispersions from rest-frame optical nebular emission lines. The sample has a median optical magnitude R=26.0, and ranges from R≃23 to R>27, corresponding to rest-frame UV absolute magnitudes M {sub UV} ≅ –22 to M {sub UV} > –18.2. Dynamical masses range from M {sub dyn} < 1.3 × 10{sup 8} M {sub ☉} to M {sub dyn} = 6.8 × 10{sup 9} M {sub ☉}, with a median value of M {sub dyn} = 6.3 × 10{sup 8} M {sub ☉}. Thirty of the 36 Lyα emission lines are redshifted with respect to the systemic velocity with at least 1σ significance, and the velocity offset with respect to systemic Δv {sub Lyα} is correlated with the R-band magnitude, M {sub UV}, and the velocity dispersion measured from nebular emission lines with >3σ significance: brighter galaxies with larger velocity dispersions tend to have larger values of Δv {sub Lyα}. We also make use of a comparison sample of 122 UV-color-selected R<25.5 galaxies at z ∼ 2, all with Lyα emission and systemic redshifts measured from nebular emission lines. Using the combined LAE and comparison samples for a total of 158 individual galaxies, we find that Δv {sub Lyα} is anti-correlated with the Lyα equivalent width with 7σ significance. Our results are consistent with a scenario in which the Lyα profile is determined primarily by the properties of the gas near the systemic redshift; in such a scenario, the opacity to Lyα photons in lower mass galaxies may be reduced if large gaseous disks have not yet developed and if the gas is ionized by the harder spectrum of young, low metallicity stars.
- OSTI ID:
- 22370105
- Journal Information:
- Astrophysical Journal, Vol. 795, 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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