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A HST/WFC3-IR Morphological Survey of Galaxies at z = 1.5-3.6. II. The Relation between Morphology and Gas-phase Kinematics

Law, David R. and Steidel, Charles C. and Shapley, Alice E. and Nagy, Sarah R. and Reddy, Naveen A. and Erb, Dawn K. (2012) A HST/WFC3-IR Morphological Survey of Galaxies at z = 1.5-3.6. II. The Relation between Morphology and Gas-phase Kinematics. Astrophysical Journal, 759 (1). Art. No. 29. ISSN 0004-637X. doi:10.1088/0004-637X/759/1/29.

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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 ~ 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 ≾ 2 kpc are substantially more likely than their larger counterparts to exhibit Lyα in emission. Although Lyα emission strength varies widely within galaxies of a given morphological type, all but one of 19 galaxies with Lyα equivalent width W_(Lyα) > 20 Å 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 ~ 0 km s^(–1) gas is responsible both for shifting the mean absorption line redshift and attenuating W_(Lyα) (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 ~ 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.

Item Type:Article
Related URLs:
URLURL TypeDescription
Law, David R.0000-0002-9402-186X
Steidel, Charles C.0000-0002-4834-7260
Shapley, Alice E.0000-0003-3509-4855
Reddy, Naveen A.0000-0001-9687-4973
Erb, Dawn K.0000-0001-9714-2758
Additional Information:© 2012 American Astronomical Society. Received 2012 June 28; accepted 2012 September 11; published 2012 October 15. Based in part on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W. M. Keck Foundation. D.R.L., C.C.S., and S.R.N. have been supported by grant GO-11694 from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. C.C.S. has been supported by the US National Science Foundation through grants AST-0606912 and AST-0908805. A.E.S. acknowledges support from the David and Lucile Packard Foundation. Finally, we extend thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests.
Funding AgencyGrant Number
NASANAS 5-26555
David and Lucile Packard FoundationUNSPECIFIED
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:galaxies: fundamental parameters; galaxies: high-redshift; galaxies: structure
Issue or Number:1
Record Number:CaltechAUTHORS:20121217-112707609
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Official Citation:A HST/WFC3-IR Morphological Survey of Galaxies at z = 1.5-3.6. II. The Relation between Morphology and Gas-phase Kinematics David R. Law, Charles C. Steidel, Alice E. Shapley, Sarah R. Nagy, Naveen A. Reddy, and Dawn K. Erb doi:10.1088/0004-637X/759/1/29
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:36011
Deposited By: Ruth Sustaita
Deposited On:17 Dec 2012 21:23
Last Modified:09 Nov 2021 23:19

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