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Mid-infrared spectroscopy of two luminous submillimeter galaxies at z~2.8

D. Lutz·E. Valiante·E. Sturm·R. Genzel·L. J Tacconi·M. D. Lehnert·A. Sternberg·A. J. Baker
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Abstract

Using the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope, we have obtained rest frame mid-infrared spectroscopy of two bright submillimeter galaxies. SMMJ02399-0136 at z=2.81 shows a superposition of PAH emission features and a mid-infrared continuum, indicating significant and roughly equal contributions to its bolometric luminosity from star formation and from a Compton-thick AGN. We derive a new redshift of z=2.80 for MMJ154127+6616 from the IRS spectrum and find this object is dominated by starburst PAH emission. The rest frame mid- to far-infrared spectral energy distributions are consistent with these submillimeter galaxies being scaled up versions of local ultraluminous infrared galaxies. The mid-infrared spectra support the scenario that submillimeter galaxies are sites of extreme star formation and represent a key phase in the formation of massive galaxies.

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D. Lutz, E. Valiante, E. Sturm, R. Genzel, L. J Tacconi, M. D. Lehnert, A. Sternberg, A. J. Baker. 2005-04-20. Mid-infrared spectroscopy of two luminous submillimeter galaxies at z~2.8. https://doi.org/10.1086/431217

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