We present galaxy MACS0416-Y1 at zspec = 8.312 as observed by the CAnadian NIRISS Unbiased Cluster Survey. MACS0416-Y1 has been shown to have extreme dust properties; thus, we study the physical properties and star formation histories of its resolved components. Overall, we find that MACS0416-Y1 is undergoing a star formation burst in three resolved clumps. The central clump is less massive compared to the other clumps and possibly formed in the merging process of the two larger clumps. Although the star formation history indicates an ongoing star formation burst, this gas-rich galaxy shows comparable star formation efficiency to cosmic noon galaxies. Using NIRSpec prism spectroscopy, we measure metallicity, , ionization parameter, , and electron temperature Te = 18000 ± 4000 K. The emission line ratios of the galaxy indicate an evolved interstellar medium similar to z ∼ 2 star-forming galaxies. Further, we find possible presence of ionization from an active galactic nucleus (AGN) using emission line diagnostics; however, we do not detect a broad-line component in the Hβ emission line. As this gas-rich galaxy is undergoing a major merger, we hypothesize that the high dust temperature in MACS0416-Y1 is caused by the star formation burst or a possible narrow-line AGN.

中文翻译：

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在极端尘埃条件下 z = 8.3 大质量合并中恒星和气体的详细研究


我们展示了 MACS0416-Y1 星系 zspec = 8.312，这是由 CAnadian NIRISS 无偏星系团巡天观测到的。MACS0416-Y1 已被证明具有极强的粉尘特性;因此，我们研究了其分辨成分的物理性质和恒星形成历史。总的来说，我们发现 MACS0416-Y1 正在经历恒星形成爆发，分为三个分辨的团块。与其他团块相比，中心团块的质量较小，可能是在两个较大团块的合并过程中形成的。尽管恒星形成历史表明恒星形成爆发仍在进行中，但这个富含气体的星系显示出与宇宙正午星系相当的恒星形成效率。使用 NIRSpec 棱镜光谱，我们测量金属丰度、电离参数和电子温度 Te = 18000 ± 4000 K。星系的发射线比表明一种演化的星际介质，类似于 z ∼ 2 个形成恒星的星系。此外，我们使用发射线诊断发现可能存在来自活跃星系核 （AGN） 的电离;然而，我们没有在 Hβ 发射线中检测到宽线成分。由于这个富含气体的星系正在经历一次重大合并，我们假设 MACS0416-Y1 中的高尘埃温度是由恒星形成爆发或可能的窄线 AGN 引起的。