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CO J = 2-1 Line Emission in Cluster Galaxies at z ~ 1: Fueling Star Formation in Dense Environments

Wagg, Jeff and Pope, Alexandra and Alberts, Stacey and Armus, Lee and Brodwin, Mark and Bussmann, Robert S. and Desai, Vandana and Dey, Arjun and Jannuzi, Buell T. and Le Floc'h, Emeric and Melbourne, Jason and Stern, Daniel (2012) CO J = 2-1 Line Emission in Cluster Galaxies at z ~ 1: Fueling Star Formation in Dense Environments. Astrophysical Journal, 752 (2). Art. No. 91. ISSN 0004-637X. doi:10.1088/0004-637X/752/2/91.

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We present observations of CO J = 2–1 line emission in infrared-luminous cluster galaxies at z ∼ 1 using the IRAM Plateau de Bure Interferometer. Our two primary targets are optically faint, dust-obscured galaxies (DOGs) found to lie within 2Mpc of the centers of two massive (>10^(14)M_☉) galaxy clusters. CO line emission is not detected in either DOG. We calculate 3σ upper limits to the CO J = 2–1 line luminosities, L_(CO) < 6.08×10^9 and <6.63×10^9 K km s^(−1) pc^2. Assuming a CO-to-H_2 conversion factor derived for ultraluminous infrared galaxies in the local universe, this translates to limits on the cold molecular gas mass of M_(H2) < 4.86×10^9 M_☉ and M_(H2) < 5.30×10^9 M_☉. Both DOGs exhibit mid-infrared continuum emission that follows a power law, suggesting that an active galactic nucleus (AGN) contributes to the dust heating. As such, estimates of the star formation efficiencies in these DOGs are uncertain. A third cluster member with an infrared luminosity, L_(IR) < 7.4×10^(11)L_☉, is serendipitously detected in CO J = 2–1 line emission in the field of one of the DOGs located roughly two virial radii away from the cluster center. The optical spectrum of this object suggests that it is likely an obscured AGN, and the measured CO line luminosity is L'_(CO)= (1.94 ± 0.35)× 10^(10) K km s^(−1) pc^2, which leads to an estimated cold molecular gas mass M_(H2)= (1.55 ± 0.28) × 10^(10)M_☉ . A significant reservoir of molecular gas in a z ∼ 1 galaxy located away from the cluster center demonstrates that the fuel can exist to drive an increase in star formation and AGN activity at the outskirts of high-redshift clusters.

Item Type:Article
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URLURL TypeDescription 10.1088/0004-637X/752/2/91DOIArticle
Pope, Alexandra0000-0001-8592-2706
Armus, Lee0000-0003-3498-2973
Brodwin, Mark0000-0002-4208-798X
Desai, Vandana0000-0002-1340-0543
Dey, Arjun0000-0002-4928-4003
Jannuzi, Buell T.0000-0002-1578-6582
Stern, Daniel0000-0003-2686-9241
Additional Information:© 2012 The American Astronomical Society. Received 2012 February 3; accepted 2012 April 12; published 2012 May 30. We thank Jan-Martin Winters, Melanie Krips, and Roberto Neri for their helpful advice and guidance with the data analysis. For their contributions to this survey, we thank Anthony Gonzalez and Thomas Soifer, as well as Adam Stanford for the LRIS spectrum. This work was co-funded under the Marie Curie Actions of the European Commission (FP7-COFUND). Some of the data presented herein were 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 the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Part of this work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Support for this work was provided by NASA. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. Based on observations carried out with the IRAM Plateau de Bure Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Marie Curie FellowshipUNSPECIFIED
W. M. Keck FoundationUNSPECIFIED
Subject Keywords: galaxies: clusters: general; galaxies: evolution; galaxies: formation; ISM: molecules
Issue or Number:2
Record Number:CaltechAUTHORS:20120724-091522155
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Official Citation: CO J = 2-1 Line Emission in Cluster Galaxies at z ~ 1: Fueling Star Formation in Dense Environments Jeff Wagg et al. 2012 ApJ 752 91
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:32662
Deposited By: Ruth Sustaita
Deposited On:24 Jul 2012 16:46
Last Modified:09 Nov 2021 21:29

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