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arXiv 1208.3464astro-ph.CO
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GOODS-South中CANDELS HST WFC3/IR成像揭示的(亚)毫米选择星系的性质

The properties of (sub)millimetre-selected galaxies as revealed by CANDELS HST WFC3/IR imaging in GOODS-South

T. A. Targett, J. S. Dunlop, M. Cirasuolo, R. J. McLure, V. A. Bruce, A. Fontana, A. Galametz, D. Paris, R. Davé, A. Dekel, S. M. Faber, H. C. Ferguson, N. A. G… 展开作者

T. A. Targett, J. S. Dunlop, M. Cirasuolo, R. J. McLure, V. A. Bruce, A. Fontana, A. Galametz, D. Paris, R. Davé, A. Dekel, S. M. Faber, H. C. Ferguson, N. A. Grogin, J. S. Kartaltepe, D. D. Kocevski, A. M. Koekemoer, P. Kurczynski, K. Lai, J. Lotz

摘要:

我们利用HST CANDELSWFC 3/IR成像研究了GOODS-South中(亚)mm星系的性质。在使用深射电和斯皮策成像来识别(亚)毫米源的星系对应物之后,我们以两种方式使用了新的CANDELS数据。首先,我们推导出了改进的光度红移和恒星质量,证实了(亚)mm星系是z=1-3的大质量(<M*>=2.2x10^11 M_solar)星系。其次,我们利用WFC 3/IR成像的深度和分辨率来确定静止帧光波长下星系的大小和形态,拟合二维轴对称Sersic模型。至关重要的是,WFC 3/IR H波段成像使质量占主导地位的星系,而不是蓝色的高表面亮度的功能,往往占主导地位的光学(静止帧紫外线)图像的(亚)毫米星系的建模,并可以混淆视觉形态分类。作为分析的结果,我们发现,在几乎所有的(亚)mm星系中,>95%的静止坐标系光学光可以很好地描述为单一的指数盘,或多组分系统,其中主要成分是盘状的。我们证明了这一结论与高质量地基K波段成像的结果是一致的,并解释了原因。大质量盘星系的主机发光(亚)毫米发射是合理的扩展(r_e=4千秒差距),与其他大质量恒星形成盘在z~2的大小一致。在许多情况下,我们在源内发现了蓝色团块的证据,质量占主导地位的圆盘在较长的波长下变得更加重要。最后,只有少数的来源显示了一个主要的星系-星系相互作用的证据。总的来说,这些结果支持了这样的观点,即大多数z~2的(亚)mm星系只是那个时代正常恒星形成星系的最极端例子。

英文摘要:

We have exploited the HST CANDELS WFC3/IR imaging to study the properties of (sub-)mm galaxies in GOODS-South. After using the deep radio and Spitzer imaging to identify galaxy counterparts for the (sub-)mm sources, we have used the new CANDELS data in two ways. First, we have derived improved photometric redshifts and stellar masses, confirming that the (sub-)mm galaxies are massive (<M*>=2.2x10^11 M_solar) galaxies at z=1-3. Second, we have exploited the depth and resolution of the WFC3/IR imaging to determine the sizes and morphologies of the galaxies at rest-frame optical wavelengths, fitting two-dimensional axi-symmetric Sersic models. Crucially, the WFC3/IR H-band imaging enables modelling of the mass-dominant galaxy, rather than the blue high-surface brightness features which often dominate optical (rest-frame UV) images of (sub-)mm galaxies, and can confuse visual morphological classification. As a result of this analysis we find that >95% of the rest-frame optical light in almost all of the (sub-)mm galaxies is well-described by either a single exponential disk, or a multiple-component system in which the dominant constituent is disk-like. We demonstrate that this conclusion is consistent with the results of high-quality ground-based K-band imaging, and explain why. The massive disk galaxies which host luminous (sub-)mm emission are reasonably extended (r_e=4 kpc), consistent with the sizes of other massive star-forming disks at z~2. In many cases we find evidence of blue clumps within the sources, with the mass-dominant disk becoming more significant at longer wavelengths. Finally, only a minority of the sources show evidence for a major galaxy-galaxy interaction. Taken together, these results support the view that most (sub-)mm galaxies at z~2 are simply the most extreme examples of normal star-forming galaxies at that era.

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