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IROCKS: Spatially Resolved Kinematics of z ~ 1 Star-forming Galaxies

Mieda, Etsuko and Wright, Shelley A. and Larkin, James E. and Armus, Lee and Juneau, Stéphanie and Salim, Samir and Murray, Norman (2016) IROCKS: Spatially Resolved Kinematics of z ~ 1 Star-forming Galaxies. Astrophysical Journal, 831 (1). Art. No. 78. ISSN 0004-637X.

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We present results from the Intermediate Redshift OSIRIS Chemo-Kinematic Survey (IROCKS) for sixteen z ~ 1 and one z ~ 1.4 star-forming galaxies. All galaxies were observed with OSIRIS with the laser guide star adaptive optics system at Keck Observatory. We use rest-frame nebular Hα emission lines to trace morphologies and kinematics of ionized gas in star-forming galaxies on sub-kiloparsec physical scales. We observe elevated velocity dispersions (σ ≳ 50 km s^(−1)) seen in z > 1.5 galaxies persist at z ~ 1 in the integrated galaxies. Using an inclined disk model and the ratio of v/σ, we find that 1/3 of the z ~ 1 sample are disk candidates while the other 2/3 of the sample are dominated by merger-like and irregular sources. We find that including extra attenuation toward H ii regions derived from stellar population synthesis modeling brings star formation rates (SFRs) using Hα and stellar population fit into a better agreement. We explore the properties of the compact Hα sub-component, or "clump," at z ~ 1 and find that they follow a similar size–luminosity relation as local H ii regions but are scaled-up by an order of magnitude with higher luminosities and sizes. Comparing the z ~ 1 clumps to other high-redshift clump studies, we determine that the clump SFR surface density evolves as a function of redshift. This suggests clump formation is directly related to the gas fraction in these systems and may support disk fragmentation as their formation mechanism since gas fraction scales with redshift.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Wright, Shelley A.0000-0003-1034-8054
Larkin, James E.0000-0001-7687-3965
Armus, Lee0000-0003-3498-2973
Salim, Samir0000-0003-2342-7501
Additional Information:© 2016. The American Astronomical Society. Received 2016 March 19; revised 2016 August 2; accepted 2016 August 18; published 2016 October 27. The Dunlap Institute is funded through an endowment established by the David Dunlap family and the University of Toronto. This research was partly supported by the Natural Sciences and Engineering Research Council (NSERC) of Canada Discovery Grant. We extend our gratitude to Nick Mostek, Alison Coil, and Bahram Mobasher for generously sharing their SED parameters for these sources. We also thank Emily Wisnioski for providing local H ii measurements used in our clump analysis. We are grateful to the Keck Observatory staff, Jim Lyke and Randy Campbell, for helping with many of the observations and the OSIRIS data reduction pipeline. We thank the referee for a thorough reading and valuable comments. The data presented herein were obtained at the WM Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the WM Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
David Dunlap familyUNSPECIFIED
University of TorontoUNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:galaxies: evolution – galaxies: high-redshift – galaxies: kinematics and dynamics – infrared: galaxies
Issue or Number:1
Record Number:CaltechAUTHORS:20161027-143113066
Persistent URL:
Official Citation:Etsuko Mieda et al 2016 ApJ 831 78
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:71560
Deposited By: George Porter
Deposited On:28 Oct 2016 16:41
Last Modified:02 Nov 2019 16:48

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