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arXiv 1610.02409astro-ph.GA
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SCUBA-2宇宙学遗产巡天:来自850微米成像的2个deg2的明亮亚毫米星系的性质

The SCUBA-2 Cosmology Legacy Survey: the nature of bright submm galaxies from 2 deg2 of 850-um imaging

Michał J. Michałowski, J. S. Dunlop, M. P. Koprowski, M. Cirasuolo, J. E. Geach, R. A. A. Bowler, A. Mortlock, K. I. Caputi, I. Aretxaga, V. Arumugam, Chian-Cho… 展开作者

Michał J. Michałowski, J. S. Dunlop, M. P. Koprowski, M. Cirasuolo, J. E. Geach, R. A. A. Bowler, A. Mortlock, K. I. Caputi, I. Aretxaga, V. Arumugam, Chian-Chou Chen, R. J. McLure, M. Birkinshaw, N. Bourne, D. Farrah, E. Ibar, P. van der Werf, M. Zemcov

摘要:

利用SCUBA-2/JCMT选择的~ 2deg 2 COSMOS和UDS场,给出了亮(S850> 4 mJy)亚毫米星系的物理性质[红移(z)、恒星形成率(SFR)和恒星质量(Mstar)]。我们完成了所有(~2000)S/N>3.5 850-um源的星系识别过程,但我们的科学分析集中在651 S/N>4源的高质量子样本上,具有完整的多波长覆盖,包括1.1-mm成像。我们检查我们的鉴定的可靠性,和SCUBA-2通量的鲁棒性,通过重新访问最近的ALMA后续的29个来源在我们的样本。考虑到大于4 mJy的ALMA源,我们的识别方法的完整性为~ 86%,可靠性为~ 92%,只有~15- 20%的源受到多重性的显著影响(当次级分量贡献>1/3的初级源通量时)。源混合对SCUBA-2确定的850 μ m源计数的影响是适度的;将单盘通量按~0.9的比例缩放可重现ALMA源计数。对于我们最终的SCUBA-2样品,我们发现中值z=2.40+0.10-0.04,SFR=287+-6Moyr-1,log(Mstar/Mo)=11.12+-0.02(后者用于349/651个具有光学识别的源)。这些属性清楚地定位在恒星形成星系的“主序列”的高质量端的明亮的submm星系到z~6,这表明主要合并不是高红移submm选择人口的主导驱动力。它们的数量密度也与演化中的星系恒星质量函数相一致。因此,submm星系的人口是预期的,尽管再现恒星形成星系的主要序列的演化仍然是理论模型/模拟的挑战。

英文摘要:

We present physical properties [redshifts (z), star-formation rates (SFRs) and stellar masses (Mstar)] of bright (S850>4mJy) submm galaxies in the ~2deg2 COSMOS and UDS fields selected with SCUBA-2/JCMT. We complete the galaxy identification process for all (~2000) S/N>3.5 850-um sources, but focus our scientific analysis on a high-quality sub-sample of 651 S/N>4 sources with complete multi-wavelength coverage including 1.1-mm imaging. We check the reliability of our identifications, and the robustness of the SCUBA-2 fluxes by revisiting the recent ALMA follow-up of 29 sources in our sample. Considering >4mJy ALMA sources, our identification method has a completeness of ~86 per cent with a reliability of ~92 per cent, and only ~15-20 per cent of sources are significantly affected by multiplicity (when a secondary component contributes >1/3 of the primary source flux). The impact of source blending on the 850-um source counts as determined with SCUBA-2 is modest; scaling the single-dish fluxes by ~0.9 reproduces the ALMA source counts. For our final SCUBA-2 sample we find median z=2.40+0.10-0.04, SFR=287+-6Moyr-1, and log(Mstar/Mo)=11.12+-0.02 (the latter for 349/651 sources with optical identifications). These properties clearly locate bright submm galaxies on the high-mass end of the 'main sequence' of star-forming galaxies out to z~6, suggesting that major mergers are not a dominant driver of the high-redshift submm-selected population. Their number densities are also consistent with the evolving galaxy stellar mass function. Hence, the submm galaxy population is as expected, albeit reproducing the evolution of the main sequence of star-forming galaxies remains a challenge for theoretical models/simulations.

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