A HST/WFC3-IR MORPHOLOGICAL SURVEY OF GALAXIES AT z = 1.5-3.6. II. THE RELATION BETWEEN MORPHOLOGY AND GAS-PHASE KINEMATICS

Journal Article · Thu Nov 01 04:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/759/1/29· OSTI ID:22086472

Law, David R ^[1]; Steidel, Charles C ^[2]; Shapley, Alice E; Nagy, Sarah R ^[3]; Reddy, Naveen A ^[4]

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1. Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, Ontario M5S 3H4 (Canada)
2. Department of Astronomy, California Institute of Technology, MS 249-17, Pasadena, CA 91125 (United States)
3. Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)
4. Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States)

We analyze rest-frame optical morphologies and gas-phase kinematics as traced by rest-frame far-UV and optical spectra for a sample of 204 star-forming galaxies in the redshift range z {approx} 2-3 drawn from the Keck Baryonic Structure Survey. We find that spectroscopic properties and gas-phase kinematics are closely linked to morphology: compact galaxies with semimajor axis radii r {approx}< 2 kpc are substantially more likely than their larger counterparts to exhibit Ly{alpha} in emission. Although Ly{alpha} emission strength varies widely within galaxies of a given morphological type, all but one of 19 galaxies with Ly{alpha} equivalent width W {sub Ly{alpha}} > 20 A have compact and/or multiple-component morphologies with r {<=} 2.5 kpc. The velocity structure of absorption lines in the galactic continuum spectra also varies as a function of morphology. Galaxies of all morphological types drive similarly strong outflows (as traced by the blue wing of interstellar absorption line features), but the outflows of larger galaxies are less highly ionized and exhibit larger optical depth at the systemic redshift that may correspond to a decreasing efficiency of feedback in evacuating gas from the galaxy. This v {approx} 0 km s{sup -1} gas is responsible both for shifting the mean absorption line redshift and attenuating W {sub Ly{alpha}} (via a longer resonant scattering path) in galaxies with larger rest-optical half-light radii. In contrast to galaxies at lower redshifts, there is no evidence for a correlation between outflow velocity and inclination, suggesting that outflows from these puffy and irregular systems may be poorly collimated. Our observations are broadly consistent with theoretical models of inside-out growth of galaxies in the young universe, in which typical z {approx} 2-3 star-forming galaxies are predominantly unstable, dispersion-dominated, systems fueled by rapid gas accretion that later form extended rotationally supported disks when stabilized by a sufficiently massive stellar component.

• OSTI ID: 22086472
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 759; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
ASTRONOMY
ASTROPHYSICS
CORRELATIONS
EMISSION SPECTRA
GALAXIES
LYMAN LINES
MORPHOLOGY
PHOTON EMISSION
RED SHIFT
RESONANCE SCATTERING
STARS
UNIVERSE
VISIBLE RADIATION