Menéndez-Delmestre, KarínBlain, Andrew W.Alexander, Dave M.Smail, IanArmus, LeeChapman, Scott C.Frayer, DaveIvison, Rob J.Teplitz, Harry2014-03-122014-03-122007-02-01Menéndez-Delmestre, Karín, Andrew W. Blain, Dave M. Alexander, Ian Smail, et al. 2007. "Mid-Infrared Spectroscopy of High Redshift Submillimeter Galaxies: First Results." The Astrophysical Journal 655(2): 65-L680004-637Xhttp://dx.doi.org/10.1086/512038http://hdl.handle.net/10222/45397We present mid-infrared spectra of 5 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 a comparison of the 7.7-micron PAH equivalent width and the PAH-to-infrared luminosity ratio of these galaxies with local templates, 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 Mrk231-type broad feature at restframe ~8 micron that does not conform to the typical 7.7/8.6 micron PAH complex in starburst galaxies, suggesting a more substantial AGN contribution.article655265