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arXiv 0910.3642astro-ph.CO
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南GOODS-South中的BLAST 250微米选定星系群

The BLAST 250-micron selected galaxy population in GOODS-South

J. S. Dunlop, P. A. R. Ade, J. J. Bock, E. L. Chapin, M. Cirasuolo, K. E. K. Coppin, M. J. Devlin, M. Griffin, T. R. Greve, J. O. Gundersen, M. Halpern, P. C. H… 展开作者

J. S. Dunlop, P. A. R. Ade, J. J. Bock, E. L. Chapin, M. Cirasuolo, K. E. K. Coppin, M. J. Devlin, M. Griffin, T. R. Greve, J. O. Gundersen, M. Halpern, P. C. Hargrave, D. H. Hughes, R. J. Ivison, J. Klein, A. Kovacs, G. Marsden, P. Mauskopf, C. B. Netterfield, L. Olmi, E. Pascale, G. Patanchon, M. Rex, D. Scott, C. Semisch, I. Smail, T. A. Targett, N. Thomas, M. D. P. Truch, C. Tucker, G. S. Tucker, M. P. Viero, F. Walter, J. L. Wardlow, A. Weiss, D. V. Wiebe

摘要:

我们确定和调查的性质,20个最亮的250微米的来源,在中央150平方米的BLAST检测。GOODS-South场的arcmin。借助于现有的深VLA无线电成像,达到S_1.4 = 30微焦耳,我们已经确定了250微米源的17/20的无线电对应物。由此产生的~1 arcsec的增强的位置精度,然后使我们能够利用GOODS-South的深多频成像,为17个无线电识别源建立安全的星系对应物,并为3个无线电未识别源建立合理的星系候选者。由于光束的尺寸很大,混淆是这次深空250微米测量的一个严重问题。然而,我们认为,我们选择的同行是显着的,往往占主导地位的贡献者测得的BLAST通量密度。对于所有这20个星系,我们已经能够确定光谱(8)或光度(12)红移。其结果是第一个“完整的”红移分布深250微米选定的星系样本。这表明,250微米的调查达到检测限~30 mJy不仅包含低红移的螺旋/LIRGs,但也极端z~2尘埃笼罩星暴星系以前发现在亚毫米波长。基于他们的IRAC颜色,我们发现,几乎所有的BLAST星系识别出现更好地描述为类似的M82星暴星系,或Sc恒星形成盘,而不是高度模糊的ULIRGs。对GOODS-South场的LABOCA 870微米成像的检查产生了7/11的z>1 BLAST源的检测,并揭示了250/870的通量密度比,其与标准40 K修正黑体拟合一致,尘埃发射率指数β =1.5。

英文摘要:

We identify and investigate the nature of the 20 brightest 250-micron sources detected by the BLAST within the central 150 sq. arcmin of the GOODS-South field. Aided by the available deep VLA radio imaging, reaching S_1.4 = 30 micro-Jy, we have identified radio counterparts for 17/20 of the 250-micron sources. The resulting enhanced positional accuracy of ~1 arcsec has then allowed us to exploit the deep multi-frequency imaging of GOODS-South to establish secure galaxy counterparts for the 17 radio-identified sources, and plausible galaxy candidates for the 3 radio-unidentified sources. Confusion is a serious issue for this deep BLAST 250-micron survey, due to the large size of the beam. Nevertheless, we argue that our chosen counterparts are significant, and often dominant contributors to the measured BLAST flux densities. For all of these 20 galaxies we have been able to determine spectroscopic (8) or photometric (12) redshifts. The result is the first `complete' redshift distribution for a deep 250-micron selected galaxy sample. This reveals that 250-micron surveys reaching detection limits of ~30 mJy contain not only low-redshift spirals/LIRGs, but also the extreme z~2 dust-enshrouded starburst galaxies previously discovered at sub-millimetre wavelengths. Based on their IRAC colours, we find that virtually all of the BLAST galaxy identifications appear better described as analogues of the M82 starburst galaxy, or Sc star-forming discs rather than highly obscured ULIRGs. Inspection of the LABOCA 870-micron imaging of the GOODS-South field yields detections of 7/11 of the z>1 BLAST sources, and reveals 250/870 flux-density ratios consistent with a standard 40K modified black-body fit with a dust emissivity index beta=1.5.

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