HerMES: spectral energy distributions of submillimeter galaxies at z > 4.

Huang, J-S, Rigopoulou, D, Magdis, G, Rowan-Robinson, M, Dai, Y, Bock, J J, Burgarella, D, Chapman, S, Clements, D L, Cooray, A, Farrah, D, Glenn, J, Oliver, S, Smith, A J, Wang, L, Page, M, Riechers, D, Roseboom, I, Symeonidis, M, Fazio, G G, Yun, M, Webb, T M A and Efstathiou, A (2014) HerMES: spectral energy distributions of submillimeter galaxies at z > 4. The Astrophysical Journal, 784 (52). ISSN 0004-637X

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Abstract

We present a study of the infrared properties for a sample of seven spectroscopically confirmed submillimetre galaxies (SMGs) at z > 4.0. By combining ground-based near-infrared, Spitzer IRAC and MIPS, Herschel SPIRE, and ground-based submillimetre / 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 <3.5μm, a hot dust component peaking at λ rest ∼ 5μm, and cold dust component which becomes significant for λ rest > 50μm. Six objects in the sample are detected at 250 and 350μm. The dust temperatures for the sources in this sample are in the range of 40–80 K, and their L FIR ∼ 10 13 Lo 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 24μmdetections corresponding to a rest-frame 4.5μm 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.

Item Type: Article
Keywords: cosmology: observations – galaxies: evolution – galaxies: formation – infrared: galaxies
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Subjects: Q Science > QB Astronomy > QB0460 Astrophysics
Depositing User: Richard Chambers
Date Deposited: 01 Jun 2015 08:30
Last Modified: 07 Mar 2017 07:33
URI: http://sro.sussex.ac.uk/id/eprint/54208

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