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arXiv 1809.01162astro-ph.GA
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z=1.6时的凝聚透镜星系的物理

Physics of a clumpy lensed galaxy at z=1.6

M. Girard, M. Dessauges-Zavadsky, D. Schaerer, J. Richard, K. Nakajima, A. Cava

摘要:

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在$z=1.5858$,位于后面的集群阿贝尔68,但强烈透镜的集群星系成员。用SINFONI/VLT在近红外线上分辨的观测结果显示了Ha、Hb、[NII]和[OIII]发射线。结合从B波段到远红外和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。我们通过运动学建模获得了$\upsilon_{rot}/σ_0 = 2.73$的稳定性,这意味着星系是由旋转主导的,但这个比例也表明,磁盘是边缘稳定的。我们发现$80\pm10$公里的$^{-1}$,可以解释在这个星系中观察到的高气体分数的$f_{gas}=0.75\pm0.15$的高固有速度色散。这种高$f_{gas}$和观测到的$\rm 3.12 \, Gyr^{-1}$的sSFR表明盘湍流和不稳定性主要由进入的气体调节。对$Q_{crit}=0.70$的Toomre稳定性判据的直接测量也可以表明准稳定厚盘的存在。最后,我们确定了三个团块在哈地图有类似的速度色散,金属丰度,似乎是嵌入在旋转盘。这三个团块共同贡献了星系SFR(Ha)上的$40\%$,并显示出SFR密度约为本地宇宙中HII区域的$100$倍。

英文摘要:

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 at $z=1.5858$, located behind the cluster Abell 68, but strongly lensed by a cluster galaxy member. Resolved observations with SINFONI/VLT in the near-infrared show Ha, Hb, [NII], and [OIII] emission lines. Combined with images covering the B band to the far-infrared 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 of $\upsilon_{rot}/σ_0 = 2.73$ 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 $80\pm10$ km s$^{-1}$ that could be explained by the high gas fraction of $f_{gas}=0.75\pm0.15$ observed in this galaxy. This high $f_{gas}$ and the observed sSFR of $\rm 3.12 \, Gyr^{-1}$ suggest that the disk turbulence and instabilities are mostly regulated by incoming gas. The direct measure of the Toomre stability criterion of $Q_{crit}=0.70$ could also indicate the presence of a quasi-stable thick disk. Finally, we identify three clumps in the Ha map which have similar velocity dispersions, metallicities, and seem to be embedded in the rotating disk. These three clumps contribute together to $40\%$ on the SFR(Ha) of the galaxy and show a SFR density about $100$ times higher than HII regions in the local Universe.

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