The LABOCA survey of the Extended Chandra Deep Field South: A photometric redshift survey of submillimetre galaxies - Astrophysics > Cosmology and Nongalactic AstrophysicsReportar como inadecuado




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Abstract: abridged We derive photometric redshifts from 17-band optical to mid-IRphotometry of 74 robust counterparts to 68 of the 126 submillimetre galaxiesSMGs selected at 870um by LABOCA observations in the ECDFS. The medianphotometric redshift of identified SMGs is z=2.2\pm0.1, the interquartile rangeis z=1.8-2.7 and we identify 10 ~15% high-redshift z>3 SMGs. We derive asimple redshift estimator for SMGs based on the 3.6 and 8um fluxes, which isaccurate to Delta z~0.4 for SMGs at z<4. A statistical analysis of sourcesaround unidentified SMGs identifies a population of likely counterparts with aredshift distribution peaking at z=2.5\pm0.3, which likely comprises ~60% ofthe unidentified SMGs. This confirms that the bulk of the undetected SMGs arecoeval with those detected in the radio-mid-IR. We conclude that ~15% of allthe SMGs are below the flux limits of our survey and lie at z>3 and hence ~30%of all SMGs have z>3. We estimate that the full S 870um>4mJy SMG population hasa median redshift of 2.5\pm0.6. In contrast to previous suggestions we find nosignificant correlation between S 870um and redshift. The median stellar massof the SMGs derived from SED fitting is 9.2\pm0.9x10^10Msun and theinterquartile range is 4.7-14x10^10Msun, although we caution that uncertaintyin the star-formation histories results in a factor of ~5 uncertainty in thesestellar masses. The median characteristic dust temperature of SMGs is35.9\pm1.4K and the interquartile range is 28.5-43.3K. The infrared luminosityfunction shows that SMGs at z=2-3 typically have higher far-IR luminosities andluminosity density than those at z=1-2. This is mirrored in the evolution ofthe star-formation rate density SFRD for SMGs which peaks at z~2. The maximumcontribution of bright SMGs to the global SFRD ~5% for SMGs with S 870um>4mJy;~50% for SMGs with S 870um>1mJy also occurs at z~2.



Autor: J. L. Wardlow 1, Ian Smail 2, K. E. K. Coppin 2, D. M. Alexander 1, W. N. Brandt 3, A. L. R. Danielson 1, B. Luo 3, A. M. Swinban

Fuente: https://arxiv.org/







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