Far-infrared and Molecular CO Emission from the Host Galaxies of Faint Quasars at z ~ 6
Abstract
We present new millimeter and radio observations of nine z ~ 6 quasars discovered in deep optical and near-infrared surveys. We observed the 250 GHz continuum in eight of the nine objects and detected three of them. New 1.4 GHz radio continuum data have been obtained for four sources, and one has been detected. We searched for molecular CO (6-5) line emission in the three 250 GHz detections and detected two of them. Combined with previous millimeter and radio observations, we study the far-infrared (FIR) and radio emission and quasar-host galaxy evolution with a sample of 18 z ~ 6 quasars that are faint at UV and optical wavelengths (rest-frame 1450 Å magnitudes of m_(1450) ≥ 20.2). The average FIR-to-active galactic nucleus (AGN) UV luminosity ratio of this faint quasar sample is about two times higher than that of the bright quasars at z ~ 6 (m_ (1450) < 20.2). A fit to the average FIR and AGN bolometric luminosities of both the UV/optically faint and bright z ~ 6 quasars, and the average luminosities of samples of submillimeter/millimeter-observed quasars at z ~ 2-5, yields a relationship of L_(FIR) ~ L_(bol)^(0.62). Five of the 18 faint z ~ 6 quasars have been detected at 250 GHz. These 250 GHz detections, as well as most of the millimeter-detected optically bright z ~ 6 quasars, follow a shallower trend of L_(FIR) ~ L_(bol)^(0.45) defined by the starburst-AGN systems in local and high-z universe. The millimeter continuum detections in the five objects and molecular CO detections in three of them reveal a few × 10^8 M_☉ of FIR-emitting warm dust and 10^(10)M_☉ of molecular gas in the quasar host galaxies. All these results argue for massive star formation in the quasar host galaxies, with estimated star formation rates of a few hundred M_☉ yr^(–1). Additionally, the higher FIR-to-AGN luminosity ratio found in these 250 GHz detected faint quasars also suggests a higher ratio between star formation rate and supermassive black hole accretion rate than the UV/optically most luminous quasars at z ~ 6.
Additional Information
© 2011 American Astronomical Society. Received 2011 April 26; accepted 2011 July 17; published 2011 August 23. This work is based on observations carried out with the Max Planck Millimeter Bolometer Array (MAMBO) on the IRAM 30 m telescope, the Plateau de Bure Interferometer, and the Very Large Array (NRAO). IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). The National Radio Astronomy Observatory (NRAO) is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. We acknowledge support from the Max-Planck Society and the Alexander von Humboldt Foundation through the Max-Planck-Forschungspreis 2005. Dominik A. Riechers acknowledges support from NASA through Hubble Fellowship grant HST-HF-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. M. A. Strauss thanks the support of NSF grant AST-0707266. Facilities: IRAM:30m (MAMBO), VLA, IRAM: InterferometerAttached Files
Published - Wang2011p16189Astron_J.pdf
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Additional details
- Eprint ID
- 27668
- Resolver ID
- CaltechAUTHORS:20111108-092731338
- Institut national des sciences de l'Univers (INSU)
- Max-Planck-Gesellschaft
- Instituto Geográfico Nacional (IGN)
- National Radio Astronomy Observatory
- NSF
- Max Planck Society
- Alexander von Humboldt Foundation
- 2005
- Max-Planck-Forschungspreis
- HST-HF-51235.01
- NASA Hubble Fellowship
- NAS 5-26555
- NASA
- AST-0707266
- NSF
- Centre National de la Recherche Scientifique (CNRS)
- Space Telescope Science Institute
- Created
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2011-11-08Created from EPrint's datestamp field
- Updated
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2021-11-09Created from EPrint's last_modified field