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Integral field spectroscopy of high-redshift star-forming galaxies with laser-guided adaptive optics: Evidence for dispersion-dominated kinematics

Law, David R. and Steidel, Charles C. and Erb, Dawn K. and Larkin, James E. and Pettini, Max and Shapley, Alice E. and Wright, Shelley A. (2007) Integral field spectroscopy of high-redshift star-forming galaxies with laser-guided adaptive optics: Evidence for dispersion-dominated kinematics. Astrophysical Journal, 669 (2). pp. 929-946. ISSN 0004-637X.

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We present early results from an ongoing study of the kinematic structure of star-forming galaxies at redshift z similar to 2-3 using integral-field spectroscopy of rest-frame optical nebular emission lines in combination with Keck laser guide star adaptive optics (LGSAO). We show kinematic maps of three target galaxies Q1623-BX453, Q0449-BX93, and DSF 2237a-C2 located at redshifts z = 2.1820, 2.0067, and 3.3172, respectively, each of which is well resolved with a PSF measuring approximately 0.11"-0.15" (similar to 900-1200 pc at z similar to 2-3) after cosmetic smoothing. Neither galaxy at z similar to 2 exhibits substantial kinematic structure on scales greater than or similar to 30 km s^(-1); both are instead consistent with largely dispersion-dominated velocity fields with sigma similar to 80 km s^(-1) along any given line of sight into the galaxy. In contrast, DSF 2237a-C2 presents a well-resolved gradient in velocity over a distance of similar to 4 kpc with peak-to-peak amplitude of 140 km s(-1). It is unlikely that DSF 2237a-C2 represents a dynamically cold rotating disk of ionized gas as the local velocity dispersion of the galaxy (sigma = 79 km s^(-1))is comparable to the observed shear. While some gas cooling models reproduce the observed kinematics better than a simple rotating disk model, even these provide a poor overall description of the target galaxies, suggesting that our current understanding of gas cooling mechanisms in galaxies in the early universe is (at best) incomplete.

Item Type:Article
Related URLs:
URLURL TypeDescription
Law, David R.0000-0002-9402-186X
Steidel, Charles C.0000-0002-4834-7260
Erb, Dawn K.0000-0001-9714-2758
Larkin, James E.0000-0001-7687-3965
Pettini, Max0000-0002-5139-4359
Shapley, Alice E.0000-0003-3509-4855
Wright, Shelley A.0000-0003-1034-8054
Additional Information:© 2007 The American Astronomical Society. Received 2007 May 16; accepted 2007 July 16. We would like to thank Andrew Benson and Juna Kollmeier for numerous helpful discussions, and Naveen Reddy for providing Spitzer photometry for Q1623-BX453. The authors also thank Randy Campbell, Al Conrad, David LeMignant, and Jim Lyke for their invaluable help obtaining the observations presented herein. D.R.L. and C.C.S. have been supported by grants AST 06-06912 and AST 03-07263 from the US National Science Foundation. Finally, we wish to extend thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Based 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.
Funding AgencyGrant Number
NSFAST 06-06912
NSFAST 03-07263
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:galaxies: high-redshift; galaxies: kinematics and dynamics; galaxies: starburst
Issue or Number:2
Record Number:CaltechAUTHORS:LAWapj07b
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11612
Deposited By: Tony Diaz
Deposited On:13 Sep 2008 01:55
Last Modified:02 Nov 2019 22:38

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