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Published March 20, 2014 | Published + Submitted
Journal Article Open

HerMES: Spectral Energy Distributions of Submillimeter Galaxies at z > 4

Abstract

We present a study of the infrared properties for a sample of seven spectroscopically confirmed submillimeter galaxies (SMGs) at z > 4.0. By combining ground-based near-infrared, Spitzer IRAC and MIPS, Herschel SPIRE, and ground-based submillimeter/millimeter photometry, we construct their spectral energy distributions (SEDs) and a composite model to fit the SEDs. The model includes a stellar emission component at λ_(rest) < 3.5 μm, a hot dust component peaking at λ_(rest) ~ 5 μm, and cold dust component which becomes significant for λ_(rest) > 50 μm. Six objects in the sample are detected at 250 and 350 μm. The dust temperatures for the sources in this sample are in the range of 40-80 K, and their L_(FIR) ~ 10^(13) L_☉ qualifies them as hyper-luminous infrared galaxies. The mean FIR-radio index for this sample is around 〈q〉 = 2.2 indicating no radio excess in their radio emission. Most sources in the sample have 24 μm detections corresponding to a rest-frame 4.5 μm luminosity of Log_(10)(L_(4.5)/L_☉) = 11 ~ 11.5. Their L_(4.5)/L_(FIR) ratios are very similar to those of starburst-dominated SMGs at z ~ 2. The L_(CO) – L_(FIR) relation for this sample is consistent with that determined for local ULIRGs and SMGs at z ~ 2. We conclude that SMGs at z > 4 are hotter and more luminous in the FIR but otherwise very similar to those at z ~ 2. None of these sources show any sign of the strong QSO phase being triggered.

Additional Information

© 2014 American Astronomical Society. Received 2013 March 14; accepted 2014 January 25; published 2014 March 4. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. 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 a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. SPIRE has been developed by a consortium of institutes led by Cardiff Univ. (UK) and including: Univ. Lethbridge (Canada); NAOC (China); CEA, LAM (France); IFSI, Univ. Padua (Italy); IAC (Spain); Stockholm Observatory (Sweden); Imperial College London, RAL, UCLMSSL, UKATC, Univ. Sussex (UK); and Caltech, JPL, NHSC, Univ. Colorado (USA). This development has been supported by national funding agencies: CSA (Canada); NAOC (China); CEA, CNES, CNRS (France); ASI (Italy); MCINN (Spain); SNSB (Sweden); STFC, UKSA (UK); and NASA (USA). Facilities: Herschel (SPIRE), Spitzer (IRAC, MIPS).

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Published - 0004-637X_784_1_52.pdf

Submitted - 1401.6079v1.pdf

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Created:
August 22, 2023
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October 26, 2023