Confirming a population of hot-dust dominated, star-forming, ultraluminous galaxies at high redshift |
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| Authors: | C M Casey S C Chapman R J Beswick A D Biggs A W Blain L J Hainline R J Ivison T W B Muxlow Ian Smail |
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| Institution: | Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA;Jodrell Bank Centre for Astrophysics, University of Manchester, Oxford Road, Manchester M13 9PL;European Southern Observatory, Garching D-85748, Germany;Department of Astronomy, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125, USA;Department of Astronomy, University of Maryland, College Park, MD 20742, USA;UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ;Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ;Institute for Computational Cosmology, Durham University, South Road, Durham DH1 3LE |
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| Abstract: | We identify eight z > 1 radio sources undetected at 850 μm but robustly detected at 70 μm, confirming that they represent ultraluminous infrared galaxies (ULIRGs) with hotter dust temperatures (〈 T d〉= 52 ± 10 K) than submillimetre galaxies (SMGs) at similar luminosities and redshifts. These galaxies share many properties with SMGs: ultraviolet spectra consistent with starbursts, high stellar masses and radio luminosities. We can attribute their radio emission to star formation since high-resolution Multi-Element Radio Linked Interferometer Network (MERLIN) radio maps show extended emission regions (with characteristic radii of 2–3 kpc), which are unlikely to be generated by active galactic nucleus (AGN) activity. These observations provide the first direct confirmation of hot, dusty ULIRGs which are missed by current submillimetre surveys. They have significant implications for future observations from the Herschel Space Observatory and Submillimetre Common-User Bolometer Array 2 (SCUBA2), which will select high-redshift luminous galaxies with less selection biases. |
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| Keywords: | galaxies: evolution galaxies: formation galaxies: high-redshift galaxies: starburst cosmology: observations |
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