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Measuring PAH Emission in Ultradeep Spitzer IRS Spectroscopy of High-Redshift IR-Luminous Galaxies

Teplitz, H. I. and Desai, V. and Armus, L. and Chary, R. and Marshall, J. A. and Colbert, J. W. and Frayer, D. T. and Pope, A. and Blain, A. and Spoon, H. W. W. and Charmandaris, V. and Scott, D. (2007) Measuring PAH Emission in Ultradeep Spitzer IRS Spectroscopy of High-Redshift IR-Luminous Galaxies. Astrophysical Journal, 659 (2). pp. 941-949. ISSN 0004-637X.

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The study of the dominant population of high-redshift IR-luminous galaxies (10^(11)-10^(12) L_☉ at 1 < z < 3), requires observation of sources at the ~0.1 mJy level in the mid-IR. We present the deepest spectra taken to date with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope. We targeted two faint (f_(24) ~ 0.15 mJy) sources in the Southern GOODS field at z = 1.09 and z = 2.69. Spectra of the lower redshift target were taken in the observed-frame 8-21 μm range, while the spectrum of the higher redshift target covered 21-37 μm. We also present the spectra of two secondary sources within the slit. We detect strong PAH emission in all four targets, and compare the spectra to those of local galaxies observed by the IRS. The z = 1.09 source appears to be a typical, star-formation-dominated IR-luminous galaxy, while the z = 2.69 source is a composite source with strong star formation and a prominent AGN. The IRAC colors of this source show no evidence of rest-frame near-IR stellar photospheric emission. We demonstrate that an AGN that contributes only a small (~10%) fraction of the bolometric luminosity can produce enough hot dust emission to overwhelm the near-IR photospheric emission from stars. Such sources would be excluded from photometric surveys that rely on the near-IR bump to identify starbursts, leading to an underestimate of the star formation rate density.

Item Type:Article
Related URLs:
URLURL TypeDescription
Teplitz, H. I.0000-0002-7064-5424
Desai, V.0000-0002-1340-0543
Armus, L.0000-0003-3498-2973
Chary, R.0000-0001-7583-0621
Marshall, J. A.0000-0001-7712-8465
Frayer, D. T.0000-0003-1924-1122
Pope, A.0000-0001-8592-2706
Blain, A.0000-0001-7489-5167
Spoon, H. W. W.0000-0002-8712-369X
Charmandaris, V.0000-0002-2688-1956
Scott, D.0000-0002-6878-9840
Additional Information:© 2007 American Astronomical Society. Print publication: Issue 2 (2007 April 20); received 2006 November 14; accepted for publication 2007 January 8. 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 an award issued by JPL/Caltech.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Subject Keywords:cosmology: observations; galaxies: evolution; galaxies: high-redshift
Issue or Number:2
Record Number:CaltechAUTHORS:20091203-165711041
Persistent URL:
Official Citation:Measuring PAH Emission in Ultradeep Spitzer IRS Spectroscopy of High-Redshift IR-Luminous Galaxies H. I. Teplitz, V. Desai, L. Armus, R. Chary, J. A. Marshall, J. W. Colbert, D. T. Frayer, A. Pope, A. Blain, H. W. W. Spoon, V. Charmandaris, and D. Scott 2007 ApJ 659 941-949 doi: 10.1086/512802
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:16872
Deposited By: Jason Perez
Deposited On:07 Dec 2009 17:33
Last Modified:16 Nov 2019 05:44

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