Fast Outflows Identified in Early Star-forming Galaxies at z = 5–6
Fast Outflows Identified in Early Star-forming Galaxies at z = 5–6
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DOI：
10.3847/1538-4357/ab49fe
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发表时间：
2019-04
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影响因子：
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通讯作者：
Y. Sugahara;M. Ouchi;Y. Harikane;N. Bouch'e;P. Mitchell;J. Blaizot
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文献类型：
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作者：
Y. Sugahara;M. Ouchi;Y. Harikane;N. Bouch'e;P. Mitchell;J. Blaizot
我们目前的速度在7个恒星形成星系z = 5-6与恒星质量的M*<$1010.1的星系外流。虽然这是具有挑战性的观测确定的外流速度，我们克服了这一点，使用阿尔马[C ii] 158 μm的发射线的系统速度和深凯克光谱与金属吸收线的速度剖面。我们用[C ii]-系统速度构造了z = 5-6星系的复合Keck谱，并拟合了复合谱中Si ii λ1260，C ii λ1335和Si iv λλ 1394，1403吸收线的流出线轮廓。我们测量的最大（90%）和中心的外流速度是和平均值，分别与低到高的电离吸收线导出的外流速度之间没有显着差异。对于M*<$1010.1，我们发现z = 5-6星系的值比z <$0星系的值高3倍，与z <$2星系相当。从恒星质量和丰度匹配结果估计晕圆速度，我们研究了α-关系。有趣的是，对于M* = 1010.0-10.8的星系，在z = 0-6的范围内，星系星星形成率与dex的小的分散度显示出明显的正相关性，这与理论预测很好地一致。这种正相关性表明，外流速度是物理相关的晕圆速度，并在固定的M* 的红移演化的增加，向高红移解释。
We present velocities of galactic outflows in seven star-forming galaxies at z = 5–6 with stellar masses of M* ∼ 1010.1 . Although it is challenging to observationally determine the outflow velocities, we overcome this by using ALMA [C ii] 158 μm emission lines for systemic velocities and deep Keck spectra with metal absorption lines for velocity profiles available to date. We construct a composite Keck spectrum of the galaxies at z = 5–6 with the [C ii]-systemic velocities, and fit outflow-line profiles to the Si ii λ1260, C ii λ1335, and Si iv λλ1394,1403 absorption lines in the composite spectrum. We measure the maximum (90%) and central outflow velocities to be and on average, respectively, showing no significant differences between the outflow velocities derived with the low- to high-ionization absorption lines. For M* ∼ 1010.1 , we find that the value of our z = 5–6 galaxies is 3 times higher than those of z ∼ 0 galaxies and comparable to z ∼ 2 galaxies. Estimating the halo circular velocity from the stellar masses and the abundance matching results, we investigate a – relation. Interestingly, for galaxies with M* = 1010.0–10.8 shows a clear positive correlation with and/or the galaxy star formation rate over z = 0–6 with a small scatter of dex, which is in good agreement with theoretical predictions. This positive correlation suggests that the outflow velocity is physically related to the halo circular velocity, and that the redshift evolution of at fixed M* is explained by the increase in toward high redshift.