Physics of a clumpy lensed galaxy at z = 1.6
Physics of a clumpy lensed galaxy at z = 1.6
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z = 1.6 时块状透镜星系的物理学
DOI：
10.1051/0004-6361/201833533
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发表时间：
2018
影响因子：
6.5
通讯作者：
Cava A.
中科院分区：
文献类型：
--
作者：
Girard M.;Dessauges-Zavadsky M.;Schaerer D.;Richard J.;Nakajima K.;Cava A.
观测表明，在高红移星系的内部结构中存在大量的恒星形成团块。一种以更高的空间分辨率详细研究这些团块的方法是利用强引力透镜的力量，它可以拉伸天空中的图像。在这项工作中，我们提出了一个分析的星团星系A68-HLS 115 atz= 1.5858，位于后面的阿贝尔68，但强烈透镜的星系团成员。SINFONI/VLT在近红外（NIR）的解析观测显示Hα、Hβ、[NII]和[OIII]发射线。结合从B波段到远红外（FIR）和CO（2-1）观测的图像，这使得该星系成为仅有的几个可以进行多波段观测的来源之一，并且有可能研究分解的恒星形成团块的性质，并对综合性质，运动学和金属丰度进行详细分析。通过对运动学的建模，我们得到了一个稳定性的α rot/σ0= 2.73，这意味着星系是由旋转主导的，但这个比率也表明盘是边缘稳定的。我们发现了80 ± 10 km s-1的高固有速度色散，这可以通过在该星系中观察到的高气体分数废气= 0.75 ± 0.15来解释。这种高的fgas和观测到的sSFR为3.12 Gyr− 1，表明盘的湍流和不稳定性主要是由进入的气体（星星形成的可用气体库）调节的。Toomre稳定性判据Qcrit = 0.70的直接测量也可以表明存在准稳定厚盘。最后，我们在Hα图中识别出三个团块，它们具有相似的速度色散、金属丰度，并且似乎嵌入在旋转的圆盘中。这三个团簇共同贡献了银河系SFRHα的约40%，并显示出星星形成率密度比本地宇宙中的HII区域高出约100倍。
Observations have shown that massive star-forming clumps are present in the internal structure of high-redshift galaxies. One way to study these clumps in detail with a higher spatial resolution is by exploiting the power of strong gravitational lensing which stretches images on the sky. In this work, we present an analysis of the clumpy galaxy A68-HLS115 atz= 1.5858, located behind the cluster Abell 68, but strongly lensed by a cluster galaxy member. Resolved observations with SINFONI/VLT in the near-infrared (NIR) show Hα, Hβ, [NII], and [OIII] emission lines. Combined with images covering theBband to the far-infrared (FIR) and CO(2–1) observations, this makes this galaxy one of the only sources for which such multi-band observations are available and for which it is possible to study the properties of resolved star-forming clumps and to perform a detailed analysis of the integrated properties, kinematics, and metallicity. We obtain a stability ofυrot/σ0= 2.73 by modeling the kinematics, which means that the galaxy is dominated by rotation, but this ratio also indicates that the disk is marginally stable. We find a high intrinsic velocity dispersion of 80 ± 10 km s−1that could be explained by the high gas fraction offgas= 0.75 ± 0.15 observed in this galaxy. This highfgasand the observed sSFR of 3.12 Gyr−1suggest that the disk turbulence and instabilities are mostly regulated by incoming gas (available gas reservoir for star formation). The direct measure of the Toomre stability criterion ofQcrit= 0.70 could also indicate the presence of a quasi-stable thick disk. Finally, we identify three clumps in the Hαmap which have similar velocity dispersions, metallicities, and seem to be embedded in the rotating disk. These three clumps contribute together to ∼40% on the SFRHαof the galaxy and show a star formation rate density about ∼100 times higher than HII regions in the local Universe.