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Decomposing Dusty Galaxies. I. Multicomponent Spectral Energy Distribution Fitting

Marshall, J. A. and Herter, T. L. and Armus, L. and Charmandaris, V. and Spoon, H. W. W. and Bernard-Salas, J. and Houck, J. R. (2007) Decomposing Dusty Galaxies. I. Multicomponent Spectral Energy Distribution Fitting. Astrophysical Journal, 670 (1). pp. 129-155. ISSN 0004-637X. doi:10.1086/521588.

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We present a new multicomponent SED decomposition method and use it to analyze the UV to millimeter wavelength SEDs of a sample of dusty infrared-luminous galaxies. Each SED is decomposed into emission from populations of stars, an AGN accretion disk, PAHs, atomic and molecular lines, and distributions of graphite and silicate grains. Decompositions of the SEDs of template starburst galaxies and AGNs provide baseline properties to aid in quantifying the strength of star formation and accretion in the composite systems NGC 6240 and Mrk 1014. We find that obscured radiation from stars is capable of powering the total dust emission from NGC 6240. The presence of a small quantity of 1260 K dust in this source suggests a ~2% AGN contribution, although we cannot rule out a larger contribution from a deeply embedded AGN visible only in X-rays. The decomposition of Mrk 1014 is consistent with ~65% of its power emerging from an AGN and ~35% from star formation. We suggest that many of the variations in our template starburst SEDs may be explained in terms of the different mean optical depths through the clouds of dust surrounding the young stars within each galaxy. Prompted by the divergent far-IR properties of our template AGNs, we suggest that variations in the relative orientation of their AGN accretion disks with respect to the disks of the galaxies hosting them may result in different amounts of AGN-heated cold dust emission emerging from their host galaxies. We estimate that 30%-50% of the far-IR and PAH emission from Mrk 1014 may originate from such AGN-heated material in its host galaxy disk.

Item Type:Article
Related URLs:
URLURL TypeDescription
Marshall, J. A.0000-0001-7712-8465
Herter, T. L.0000-0002-3856-8385
Armus, L.0000-0003-3498-2973
Charmandaris, V.0000-0002-2688-1956
Spoon, H. W. W.0000-0002-8712-369X
Bernard-Salas, J.0000-0002-8452-8675
Additional Information:© 2007 The American Astronomical Society. Received 2006 August 22; accepted 2007 July 11. We would like to thank Moshe Elitzur, Vandana Desai, and Kieran Cleary for many helpful discussions. We also wish to acknowledge the assistance of the anonymous referee, whose review has resulted in a much improved paper. 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 1257184 issued by JPL/Caltech. 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.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Subject Keywords:galaxies : Seyfert; galaxies : starburst; infrared : galaxies; methods : numerical
Issue or Number:1
Record Number:CaltechAUTHORS:20100318-133247017
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:17771
Deposited By: Tony Diaz
Deposited On:21 Mar 2010 17:35
Last Modified:08 Nov 2021 23:38

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