Open AccessMid-Infrared Spectroscopy of High-Redshift Submillimeter Galaxies: First Results
Author(s) -
Karín MenéndezDelmestre,
A. W. Blain,
D. M. Alexander,
Ian Smail,
L. Armus,
S. C. Chapman,
D. T. Frayer,
R. J. Ivison,
Harry I. Teplitz
Publication year - 2007
Publication title -
the astrophysical journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.376
H-Index - 489
eISSN - 1538-4357
pISSN - 0004-637X
DOI - 10.1086/512038
Subject(s) - physics , astrophysics , luminous infrared galaxy , galaxy , luminosity , spitzer space telescope , redshift , star formation , infrared , astronomy , spectroscopy , telescope
We present mid-infrared spectra of 5 submillimeter galaxies at z=0.65-2.38taken with the Spitzer Space Telescope. Four of these sources, at z<1.5, havestrong PAH features and their composite spectrum is well fitted by an M82-likespectrum with an additional power-law component consistent with that expectedfrom AGN activity. Based on a comparison of the 7.7-micron PAH equivalent widthand the PAH-to-infrared luminosity ratio of these galaxies with localtemplates, we conclude that these galaxies host both star-formation and AGNactivity, with star-formation dominating the bolometric luminosity. The sourceat z=2.38 displays a Mrk231-type broad feature at restframe ~8 micron that doesnot conform to the typical 7.7/8.6 micron PAH complex in starburst galaxies,suggesting a more substantial AGN contribution.Comment: 4 pages, 2 figures; accepted to ApJ Letter, small changes from submitted versio
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