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The Nature of Deeply Buried Ultraluminous Infrared Galaxies: A Unified Model for Highly Obscured Dusty Galaxy Emission

Marshall, J. A. and Elitzur, M. and Armus, L. and Díaz-Santos, T. and Charmandaris, V. (2018) The Nature of Deeply Buried Ultraluminous Infrared Galaxies: A Unified Model for Highly Obscured Dusty Galaxy Emission. Astrophysical Journal, 858 (1). Art. No. 59. ISSN 1538-4357. doi:10.3847/1538-4357/aabcc0.

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We present models of deeply buried ultraluminous infrared galaxy (ULIRG) spectral energy distributions (SEDs) and use them to construct a three-dimensional diagram for diagnosing the nature of observed ULIRGs. Our goal is to construct a suite of SEDs for a very simple model ULIRG structure, and to explore how well this simple model can (by itself) explain the full range of observed ULIRG properties. We use our diagnostic to analyze archival Spitzer Space Telescope Infrared Spectrograph data of ULIRGs and find that: (1) in general, our model does provide a comprehensive explanation of the distribution of mid-IR ULIRG properties; (2) >75% (in some cases 100%) of the bolometric luminosities of the most deeply buried ULIRGs must be powered by a dust-enshrouded active galactic nucleus; (3) an unobscured "keyhole" view through ≾ 10% of the obscuring medium surrounding a deeply buried ULIRG is sufficient to make it appear nearly unobscured in the mid-IR; (4) the observed absence of deeply buried ULIRGs with large polycyclic aromatic hydrocarbon (PAH) equivalent widths is naturally explained by our models, showing that deep absorption features are "filled-in" by small quantities of foreground unobscured PAH emission (e.g., from the host galaxy disk) at the level of ~1% the bolometric nuclear luminosity. The modeling and analysis we present will also serve as a powerful tool for interpreting the high angular resolution spectra of high-redshift sources to be obtained with the James Webb Space Telescope.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Marshall, J. A.0000-0001-7712-8465
Elitzur, M.0000-0001-8143-3550
Armus, L.0000-0003-3498-2973
Díaz-Santos, T.0000-0003-0699-6083
Charmandaris, V.0000-0002-2688-1956
Additional Information:© 2018. The American Astronomical Society. Received 2017 August 11; revised 2018 April 5; accepted 2018 April 5; published 2018 May 4. The authors greatly appreciate the detailed and constructive comments of the anonymous referee which substantially improved the clarity of the manuscript. This work is based (in part) on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under NASA contract 1407. Support for this work was provided by NASA through Contract Number 1257184 issued by JPL/Caltech. M.E. acknowledges NASA support through grants NNX11AD76G and NNX15AC83G. This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. T.D.-S. acknowledges support from ALMA-CONICYT project 31130005 and FONDECYT regular project 1151239.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)31130005
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1151239
Subject Keywords:galaxies: active; galaxies: ISM; galaxies: starburst; infrared: galaxies
Issue or Number:1
Record Number:CaltechAUTHORS:20180504-102729846
Persistent URL:
Official Citation:J. A. Marshall et al 2018 ApJ 858 59
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:86226
Deposited By: George Porter
Deposited On:07 May 2018 14:21
Last Modified:15 Nov 2021 20:36

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