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Molecular Gas in z ~ 6 Quasar Host Galaxies

Wang, Ran and Carilli, Chris L. and Neri, R. and Riechers, D. A. and Wagg, Jeff and Walter, Fabian and Bertoldi, Frank and Menten, Karl M. and Omont, Alain and Cox, Pierre and Fan, Xiaohui (2010) Molecular Gas in z ~ 6 Quasar Host Galaxies. Astrophysical Journal, 714 (1). pp. 699-712. ISSN 0004-637X.

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We report our new observations of redshifted carbon monoxide emission from six z ~ 6 quasars, using the IRAM Plateau de Bure Interferometer. CO (6-5) or (5-4) line emission was detected in all six sources. Together with two other previous CO detections, these observations provide unique constraints on the molecular gas emission properties in these quasar systems close to the end of the cosmic re-ionization. Complementary results are also presented for low-J CO lines observed at the Green Bank Telescope and the Very Large Array, and dust continuum from five of these sources with the SHARC-II bolometer camera at the Caltech Submillimeter Observatory. We then present a study of the molecular gas properties in our combined sample of eight CO-detected quasars at z ~ 6. The detections of high-order CO line emission in these objects indicates the presence of highly excited molecular gas, with estimated masses on the order of 10^(10) M_☉ within the quasar host galaxies. No significant difference is found in the gas mass and CO line width distributions between our z ~ 6 quasars and samples of CO-detected 1.4 ≤ z ≤ 5 quasars and submillimeter galaxies. Most of the CO-detected quasars at z ~ 6 follow the far-infrared-CO luminosity relationship defined by actively star-forming galaxies at low and high redshifts. This suggests that ongoing star formation in their hosts contributes significantly to the dust heating at FIR wavelengths. The result is consistent with the picture of galaxy formation co-eval with supermassive black hole (SMBH) accretion in the earliest quasar-host systems. We investigate the black hole-bulge relationships of our quasar sample, using the CO dynamics as a tracer for the dynamical mass of the quasar host. The median estimated black hole-bulge mass ratio is about 15 times higher than the present-day value of ~0.0014. This places important constraints on the formation and evolution of the most massive SMBH-spheroidal host systems at the highest redshift.

Item Type:Article
Related URLs:
URLURL TypeDescription
Wang, Ran0000-0003-4956-5742
Carilli, Chris L.0000-0001-6647-3861
Neri, R.0000-0002-7176-4046
Riechers, D. A.0000-0001-9585-1462
Walter, Fabian0000-0003-4793-7880
Bertoldi, Frank0000-0002-1707-1775
Menten, Karl M.0000-0001-6459-0669
Omont, Alain0000-0002-4721-3922
Cox, Pierre0000-0003-2027-8221
Fan, Xiaohui0000-0003-3310-0131
Additional Information:© 2010 American Astronomical Society. Received 2009 December 15; accepted 2010 February 5; published 2010 April 14. This work is based on observations carried out with the IRAM PdBI, the GBT (NRAO), the VLA (NRAO), and the SHARC-II bolometer camera at the CSO. IRAM is supported by INSU/ CNRS (France), MPG (Germany), and IGN (Spain). The CSO is supported by the NSF under AST-0540882. The National Radio Astronomy Observatory (NRAO) is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. We thank the anonymous referee for useful comments. R.W. thanks Dr. Alexandre Beelen at Institut d’Astrophysique Spatiale for helpful discussions and suggestions. We acknowledge support from the Max-Planck Society and the Alexander von Humboldt Foundation through the Max-Planck-Forschungspreis 2005. D.A.R. acknowledges support from NASA through Hubble Fellowship grant HSTHF- 51235.01 awarded by 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. R.W. acknowledges support of the National Natural Science Foundation of China grant 10833006 and grant 0816341034. Facilities: IRAM:30m (MAMBO), VLA, Sloan (SDSS) CSO (SHARC-II), GBT
Funding AgencyGrant Number
Max-Planck SocietyUNSPECIFIED
Alexander von Humboldt FoundationUNSPECIFIED
NASA Hubble FellowshipHST-HF-51235.01
National Natural Science Foundation of China 10833006
National Natural Science Foundation of China 0816341034
Subject Keywords:galaxies: active; galaxies: high-redshift; galaxies: starburst; molecular data; radio lines: galaxies
Issue or Number:1
Classification Code:PACS: 98.54.Aj; 98.62.Bj; 98.62..Js; 95.85.Bh; 98.62.Py
Record Number:CaltechAUTHORS:20100520-112928959
Persistent URL:
Official Citation:Ran Wang et al 2010 ApJ 714 699 doi: 10.1088/0004-637X/714/1/699
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:18361
Deposited By: Jason Perez
Deposited On:21 May 2010 20:18
Last Modified:03 Oct 2019 01:41

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