ON THE NATURE OF THE FIRST GALAXIES SELECTED AT 350 mum
- Pontificia Universidad Catolica, Departamento de AstronomIa y Astrofisica, 4860 Vicuna Mackenna, Casilla 306, Santiago 22 (Chile)
- Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom)
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
- Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom)
- Observational Cosmology Laboratory (Code 665), NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
- School of Physics and Astronomy, Cardiff University, Queens Buildings, Cardiff, CF24 3AA (United Kingdom)
- Astronomy Centre, University of Sussex, Falmer, Brighton (United Kingdom)
- Department of Astronomy, Cornell University, 610 Space Sciences Building, Ithaca, NY 14853 (United States)
- Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96815 (United States)
- Department of Astronomy, University of Padova, Vicolo Osservatorio 3, I-35122, Padova (Italy)
- Department of Physics and Astronomy, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom)
We present constraints on the nature of the first galaxies selected at 350 mum. The sample includes galaxies discovered in the deepest blank-field survey at 350 mum (in the Booetes Deep Field) and also later serendipitous detections in the Lockman Hole. In determining multiwavelength identifications, the 350 mum position and map resolution of the second generation Submillimeter High Angular Resolution Camera are critical, especially in the cases where multiple radio sources exist and the 24 mum counterparts are unresolved. Spectral energy distribution templates are fitted to identified counterparts, and the sample is found to comprise IR-luminous galaxies at 1 < z < 3 predominantly powered by star formation. The first spectrum of a 350 mum selected galaxy provides an additional confirmation, showing prominent dust grain features typically associated with star-forming galaxies. Compared to submillimeter galaxies selected at 850 and 1100 mum, galaxies selected at 350 mum have a similar range of far-infrared color temperatures. However, no 350 mum selected sources are reliably detected at 850 or 1100 mum. Galaxies in our sample with redshifts 1 < z < 2 show a tight correlation between the far- and mid-infrared flux densities, but galaxies at higher redshifts show a large dispersion in their mid- to far-infrared colors. This implies a limit to which the mid-IR emission traces the far-IR emission in star-forming galaxies. The 350 mum flux densities (15 < S{sub 350} < 40 mJy) place these objects near the Herschel/SPIRE 350 mum confusion threshold, with the lower limit on the star formation rate density suggesting the bulk of the 350 mum contribution will come from less luminous infrared sources and normal galaxies. Therefore, the nature of the dominant source of the 350 mum background-star-forming galaxies in the epoch of peak star formation in the universe-could be more effectively probed using ground-based instruments with their angular resolution and sensitivity offering significant advantages over space-based imaging.
- OSTI ID:
- 21378212
- Journal Information:
- Astrophysical Journal, Vol. 706, Issue 1; Other Information: DOI: 10.1088/0004-637X/706/1/319; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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