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HAL - OMP | |
| HAL : hal-00660262, version 1 |
| arXiv : 1108.2406 |
| Code Bibliographique ADS : 2011A&A...534A.124B |
| DOI : 10.1051/0004-6361/201117338 |
| Fiche détaillée |  Récupérer au format |
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| Astronomy & Astrophysics 534 (2011) 124 |
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| Far-infrared constraints on the contamination by dust-obscured galaxies of high-z dropout searches |
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| F. Boone 1D. Schaerer 1 |
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| (10/2011) |
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| The spectral energy distributions (SED) of dusty galaxies at intermediate redshift may look similar to very high-redshift galaxies in the optical/near infrared (NIR) domain. This can lead to the contamination of high-redshift galaxy searches based on broad-band optical/NIR photometry by lower redshift dusty galaxies because both kind of galaxies cannot be distinguished. The contamination rate could be as high as 50%. This work shows how the far-infrared (FIR) domain can help to recognize likely low-z interlopers in an optical/NIR search for high-z galaxies. We analyze the FIR SEDs of two galaxies that are proposed to be very high-redshift (z > 7) dropout candidates based on deep Hawk-I/VLT observations. The FIR SEDs are sampled with PACS/Herschel at 100 and 160 μm, with SPIRE/Herschel at 250, 350 and 500 μm and with LABOCA/APEX at 870 μm. We find that redshifts > 7 would imply extreme FIR SEDs (with dust temperatures >100 K and FIR luminosities >1013 L&sun;). At z ~ 2, instead, the SEDs of both sources would be compatible with those of typical ultra luminous infrared galaxies or submillimeter galaxies. Considering all available data for these sources from visible to FIR we re-estimate the redshifts and find z ~ 1.6-2.5. Owing to the strong spectral breaks observed in these galaxies, standard templates from the literature fail to reproduce the visible-to-near-IR part of the SEDs even when additional extinction is included. These sources strongly resemble dust-obscured galaxies selected in Spitzer observations with extreme visible-to-FIR colors, and the galaxy GN10 at z = 4. Galaxies with similar SEDs could contaminate other high-redshift surveys. |
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| 1 : | Institut de recherche en astrophysique et planétologie (IRAP) |
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CNRS : UMR5277 – Université Paul Sabatier [UPS] - Toulouse III – Observatoire Midi-Pyrénées |
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| 2 : | Max-Planck-Institut für extraterrestrische Physik |
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Max-Planck-Institut |
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| 3 : | Max-Planck-Institut für Radioastronomie (MPIFR) |
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Max-Planck-Institut |
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| 4 : | Steward Observatory |
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University of Arizona |
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| 5 : | Institute for Computational Cosmology (ICC) |
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University of Durham |
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| 6 : | Alfred Wegener Institute for Polar and Marine Research |
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Helmholtz Center for Polar and Marine Research |
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| 7 : | Royal Observatory Edinburgh |
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Royal Observatory Edinburgh |
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| 8 : | Institut d'astrophysique spatiale (IAS) |
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CNRS : UMR8617 – INSU – Université Paris XI - Paris Sud |
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| 9 : | LVMT (LVMT) |
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Université Paris-Est Marne-la-Vallée (UPEMLV) |
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| 10 : | Department of Astronomy |
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California Institute of Technology |
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| 11 : | Centre de Recherche Astrophysique de Lyon (CRAL) |
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CNRS : UMR5574 – INSU – Université Claude Bernard - Lyon I – École Normale Supérieure - Lyon |
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| 12 : | Laboratoire d'Astrophysique de Marseille (LAM) |
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CNRS : UMR6110 – INSU – Université de Provence - Aix-Marseille I |
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| 13 : | Observatoire de Geneve |
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University of Geneva |
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| 14 : | XMM-Newton Science Operations Centre |
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European Space Agency |
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| 15 : | Leiden Observatory |
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University of Leiden |
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| 16 : | Departamento de Física y Astronomía |
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Universidad Complutense Madrid |
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| Domaine | : | Planète et Univers/Astrophysique/Cosmologie et astrophysique extra-galactique Physique/Astrophysique/Cosmologie et astrophysique extra-galactique |
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| galaxies: distances and redshifts – dust – extinction – gravitational lensing: weak – galaxies: high-redshift |
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| Lien vers le texte intégral : |
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| http://fr.arXiv.org/abs/1108.2406 |
| hal-00660262, version 1 | |
| http://hal.archives-ouvertes.fr/hal-00660262 | |
| oai:hal.archives-ouvertes.fr:hal-00660262 | |
| Contributeur : Johan Richard | |
| Soumis le : Lundi 16 Janvier 2012, 11:56:38 | |
| Dernière modification le : Mercredi 18 Janvier 2012, 16:38:49 | |
