CaltechAUTHORS
Published February 1, 2007 | Version Published
Journal Article Open

Mid-Infrared Spectroscopy of High-Redshift Submillimeter Galaxies: First Results

Creators

  • 1. ROR icon California Institute of Technology
  • 2. ROR icon Durham University
  • 3. ROR icon University of Cambridge
  • 4. ROR icon University of Victoria
  • 5. ROR icon UK Astronomy Technology Centre
  • 6. ROR icon Royal Observatory

Abstract

We present mid-infrared spectra of five submillimeter galaxies at z = 0.65-2.38 taken with the Spitzer Space Telescope. Four of these sources, at z ≾ 1.5, have strong PAH features and their composite spectrum is well fitted by an M82-like spectrum with an additional power-law component consistent with that expected from AGN activity. Based on comparison with local templates of the 7.7 μm PAH equivalent width and the PAH-to-infrared luminosity ratio, we conclude that these galaxies host both star formation and AGN activity, with star formation dominating the bolometric luminosity. The source at z = 2.38 displays a Mrk 231-type broad emission feature at rest frame ~8 μm that does not conform to the typical 7.7 μm/8.6 μm PAH complex in starburst galaxies, suggesting a more substantial AGN contribution.

Additional Information

© 2007 The American Astronomical Society. Received 2006 October 30; accepted 2006 December 21; published 2007 January 12. We thank our anonymous referee for valuable comments. We thank the Spitzer Science Center staff for their support, particularly Patrick Ogle for his help in the optimization of the spectral extraction. A. W. B. thanks the Research Corporation and the Alfred P. Sloan Foundation. D. M. A. and I. S. acknowledge support from the Royal Society. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech.

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Additional details

Identifiers

Eprint ID
17556
Resolver ID
CaltechAUTHORS:20100222-144843965

Funding

Research Corporation
Alfred P. Sloan Foundation
Royal Society
NASA/JPL/Caltech

Dates

Created
2010-03-02
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Updated
2021-11-08
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Caltech groups
Infrared Processing and Analysis Center (IPAC)