Saturday, September 5, 2009

The SCUBA HAlf Degree Extragalactic Survey (SHADES) - VII. Optical/IR photometry and stellar masses of submillimetre galaxies.

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We present estimates of the photometric redshifts, stellar masses and star formation histories of sources in the Submillimetre Common-User Bolometer Array (SCUBA) HAlf Degree Extragalactic Survey (SHADES). This paper describes the 60 SCUBA sources detected in the Lockman Hole covering an area of [proportional to]320 arcmin.sup.2. Using photometry spanning the B band to 8 [mu]m, we find that the average SCUBA source forms a significant fraction of its stars in an early period of star formation and that most of the remainder forms in a shorter more intense burst around the redshift it is observed. This trend does not vary significantly with source redshift. However, the sources show a clear increase in stellar mass with redshift, consistent with downsizing. In terms of spectral energy distribution types, only two out of the 51 sources we have obtained photometric redshifts for are best fitted by a quasar-like spectrum, with approximately 80 per cent of the sources being best fitted with late-type spectra (Sc, Im and starburst). By including photometry at 850 [mu]m, we conclude that the average SCUBA source is forming stars at a rate somewhere between 6 and 30 times the rate implied from the rest-frame optical in a dust obscured burst and that this burst creates 15-65 per cent of the total stellar mass. Using a simplistic calculation, we estimate from the average star formation history that between one in five and one in 15 bright (L.sub.*+ 2 < L.sub.optical < L.sub.*- 1 mag) galaxies in the field over the interval 0 < z < 3 will at some point in their lifetime experience a similar energetic dusty burst of star formation. Finally, we compute the evolution of the star formation rate density and find it peaks around z[proportional to] 2 .

Author Affiliation:

(1)Cardiff University, School of Physics & Astronomy, Queens Buildings, The Parade, Cardiff CF24 3AA

(2)Instituto Nacional de Astrofisica, Optica y Electronica (INAOE), Aptdo. Postal 51 y 216, 72000 Puebla, Pue., Mexico

(3)Astrophysics Group, Department of Physics and Astronomy, The Open University, Milton Keynes MK7 6AA

(4)SUPA[dagger], Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ

(5)Astrophysics Group, Blackett Laboratory, Imperial College, Prince Consort Road, London SW7 2BW

(6)Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA

(7)Institute for Computational Cosmology, Department of Physics, Durham University, Durham DH1 3LE

(8)The School of Physics & Astronomy, University of Nottingham University Park, Nottingham NG7 2RD

(9)Steward Observatory, University of Arizona, 933 N. Cherry Avenue, Tuscon, AZ 85721, USA

(10)Department of Astronomy, 610 Space Sciences Building, Cornell University, Ithaca, NY 14853, USA

(11)Institute for Astro- and Particle Physics, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria

(12)Department of Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada V6T 1Z1

(13)Centre for Astrophysics Research, University of Hertfordshire, Hatfield AL10 9AB

(14)Astrophysics Research Institute, Liverpool John Moores University, Egerton Wharf, Birkenhead CH41 1LD

(15)Institute of Space and Astronautical Science, Yoshinodai 3-1-1, Sagamihara, Kanagawa 229 8510, Japan

(16)National Astronomical Observatory of Japan, 650 North A'ohoku Place, Hilo, HI 96720, USA

(17)Department of Astronomy, Vicolo dell'Osservatorio 3, University of Padova, I-35122 Padova, Italy

Article History:

Accepted 2008 February 14. Received 2008 February 4; in original form 2007 September 7

Article note:

(★) E-mail: ([dagger]) Scottish Universities Physics Alliance.

Source Citation:"The SCUBA HAlf Degree Extragalactic Survey (SHADES) - VII. Optical/IR photometry and stellar masses of submillimetre galaxies." Monthly Notices of the Royal Astronomical Society 386.2 (May 2008): 1107(24). Academic OneFile. Gale. Alachua County Library District. 5 Sept. 2009

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