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Water Vapor Emission Reveals a Highly Obscured, Star-forming Nuclear Region in the QSO Host Galaxy APM 08279+5255 at z = 3.9

van der Werf, Paul P. and Alba, A. Berciano and Spaans, M. and Loenen, A. F. and Meijerink, R. and Riechers, D. A. and Cox, P. and Weiß, A. and Walter, F. (2011) Water Vapor Emission Reveals a Highly Obscured, Star-forming Nuclear Region in the QSO Host Galaxy APM 08279+5255 at z = 3.9. Astrophysical Journal Letters, 741 (2). Art. No. L38. ISSN 2041-8205. https://resolver.caltech.edu/CaltechAUTHORS:20111214-093211915

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Abstract

We present the detection of four rotational emission lines of water vapor, from energy levels E_u/k = 101-454 K, in the gravitationally lensed z = 3.9 QSO host galaxy APM 08279+5255. While the lowest H_2O lines are collisionally excited in clumps of warm, dense gas (density of hydrogen nuclei n_H =(3.1 ± 1.2) x 10^6 cm^-3, gas temperature T_g ~ 105 ± 21 K), we find that the excitation of the higher lines is dominated by the intense local infrared radiation field. Since only collisionally excited emission contributes to gas cooling, we conclude that H2O is not a significant coolant of the warm molecular gas. Our excitation model requires the radiatively excited gas to be located in an extended region of high 100 μm opacity (τ_(100) = 0.9 ± 0.2). Locally, such extended infrared-opaque regions are found only in the nuclei of ultraluminous infrared galaxies. We propose a model where the infrared-opaque circumnuclear cloud, which is penetrated by the X-ray radiation field of the QSO nucleus, contains clumps of massive star formation where the H_2O emission originates. The radiation pressure from the intense local infrared radiation field exceeds the thermal gas pressure by about an order of magnitude, suggesting close to Eddington-limited star formation in these clumps.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1088/2041-8205/741/2/L38DOIArticle
http://iopscience.iop.org/2041-8205/741/2/L38/PublisherArticle
ORCID:
AuthorORCID
van der Werf, Paul P.0000-0001-5434-5942
Riechers, D. A.0000-0001-9585-1462
Cox, P.0000-0003-2027-8221
Weiß, A.0000-0003-4678-3939
Walter, F.0000-0003-4793-7880
Additional Information:© 2011 The American Astronomical Society. Received 2011 June 23; accepted 2011 September 2; published 2011 October 21. This work is based on observations carried out with the IRAM Plateau de Bure Interferometer. IRAM is supported by INSU/CNRS (France),MPG (Germany) and IGN (Spain). D.R. acknowledges support from NASA through a Spitzer grant. We thank Melanie Krips for expert assistance with the IRAM data reduction and Rodrigo Ibata for providing the NICMOS image used in Figure 1.We also thank Xander Tielens for commenting on an earlier version of this Letter. Facility: IRAM:Interferometer
Funders:
Funding AgencyGrant Number
Institut national des sciences de l'Univers (INSU)UNSPECIFIED
Max Planck GesellschaftUNSPECIFIED
Instituto Geográfico Nacional (IGN)UNSPECIFIED
NASAUNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Subject Keywords:galaxies: ISM; galaxies: nuclei; quasars: individual (APM 08279+5255)
Issue or Number:2
Record Number:CaltechAUTHORS:20111214-093211915
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20111214-093211915
Official Citation:Water Vapor Emission Reveals a Highly Obscured, Star-forming Nuclear Region in the QSO Host Galaxy APM 08279+5255 at z = 3.9 Paul P. van der Werf et al. 2011 ApJ 741 L38
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:28462
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:14 Dec 2011 17:56
Last Modified:03 Oct 2019 03:32

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