We present structural parameters and morphological properties of faint 450 μm selected submillimeter galaxies (SMGs) from the JCMT Large Program, STUDIES, in the COSMOS-CANDELS region. Their properties are compared to an 850 μm selected and a matched star-forming samples. We investigate stellar structures of 169 faint 450 μm sources (S 450 = 2.8–29.6 mJy; S/N > 4) at z?HST near-infrared observations. Based on our spectral energy distribution fitting, half of such faint SMGs (L IR = 1011.65±0.98 L ⊙) lie above the star formation rate (SFR)/stellar mass plane. The size–mass relation shows that these SMGs are generally similar to less-luminous star-forming galaxies selected by NUV???r versus r???J colors. Because of the intrinsic luminosity of the sample, their rest-frame optical emission is less extended than the 850 μm sources (S 850 > 2 mJy) and more extended than the star-forming galaxies in the same redshift range. For the stellar mass and SFR-matched sample at z??1 and z??2, the size differences are marginal between faint SMGs and the matched galaxies. Moreover, faint SMGs have similar Sérsic indices and projected axis ratios as star-forming galaxies with the same stellar mass and SFR. Both SMGs and the matched galaxies show high fractions (~70%) of disturbed features at z??2, and the fractions depend on the SFRs. These suggest that their star formation activity is related to galaxy merging and the stellar structures of SMGs are similar to those of star-forming galaxies. We show that the depths of submillimeter surveys are approaching the lower luminosity end of star-forming galaxies, allowing us to detect galaxies on the main sequence.
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机译：我们从COSMOS-CANDELS区域的JCMT大型计划“研究”中提出了微弱的450μm选定的亚毫米级星系（SMG）的结构参数和形态学特性。将其性能与选择的850μm样品和匹配的恒星形成样品进行比较。我们在z？HST近红外观测中研究了169个微弱的450μm光源（S 450 = 2.8-29.6 mJy; S / N> 4）的恒星结构。根据我们的光谱能量分布拟合，此类微弱的SMG（L IR = 1011.65±0.98 L half）的一半位于恒星形成率（SFR）/星体质量平面以上。大小-质量关系表明，这些SMG通常类似于NUV？r与r？J颜色选择的发光度较低的恒星形成星系。由于样品的固有发光度，它们的其余帧的光发射比850μm光源的发射范围小（S 850> 2 mJy），比同等红移范围内的恒星系的发射范围大。对于z ?? 1和z ?? 2的恒星质量和SFR匹配的样本，微弱的SMG和匹配的星系之间的大小差异很小。此外，微弱的SMG具有与恒星质量和SFR相同的恒星形成星系相似的Sérsic指数和投影轴比。 SMG和匹配星系都在zθ2处显示出高比例（〜70％）的扰动特征，并且比例取决于SFR。这些表明它们的恒星形成活动与星系合并有关，SMG的恒星结构与恒星形成星系相似。我们表明，亚毫米调查的深度接近恒星形成星系的较低光度末端，从而使我们能够检测出主要序列上的星系。
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