Diagnostics for PopIII galaxies and direct collapse black holes in the early universe
Diagnostics for PopIII galaxies and direct collapse black holes in the early universe
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早期宇宙中 PopIII 星系和直接塌缩黑洞的诊断
DOI：
10.1093/mnras/stac1242
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发表时间：
2022
影响因子：
4.8
通讯作者：
Maiolino R
中科院分区：
文献类型：
--
作者：
Nakajima K;Maiolino R
即将到来的观测设施将使早期宇宙的探索成为常规，可能探测金属丰度非常低的大量星系。因此，在如此低金属丰度的情况下，能够可靠地识别和区分不同类别的物体的诊断将是重要的。我们使用新的光电离模型来开发涉及各种星云线的诊断图。我们表明，这些图的组合允许识别和区分早期宇宙中的以下类别的物体：原始环境中的PopIII和直接坍缩黑洞（DCBH），嵌入在轻度富集的星际介质中的PopIII和DCBH (ISM;)，以及（金属贫乏的）PopII和活动星系核在富集的ISM中。涉及静架光学线路的诊断（将由詹姆斯·韦伯太空望远镜访问）具有更好的区分能力，但静架紫外线诊断也可以提供非常有用的信息。有趣的是，我们发现像[Oiii]λ5007和Civλ1549这样的金属谱线可以保持相对强（分别是相对H β和λ1640的0.1-1因子），即使在金属极度缺乏的环境中（），也可能嵌入PopIII星系和DCBH。
Forthcoming observational facilities will make the exploration of the early universe routine, likely probing large populations of galaxies at very low metallicities. It will therefore be important to have diagnostics that can solidly identify and distinguish different classes of objects in such low metallicity regimes. We use new photoionization models to develop diagnostic diagrams involving various nebular lines. We show that combinations of these diagrams allow the identification and discrimination of the following classes of objects in the early universe: PopIII and direct collapse black holes (DCBH) in pristine environments, PopIII and DCBH embedded in slightly enriched interstellar medium (ISM;), and (metal poor) PopII and active galactic nucleus in enriched ISM. Diagnostics involving rest-frame optical lines (that will be accessible byJames Webb Space Telescope) have a better discriminatory power but also rest-frame ultraviolet diagnostics can provide very useful information. Interestingly, we find that metal lines such as [Oiii]λ5007 and Civλ1549 can remain relatively strong (about a factor of 0.1–1 relative H β and Heiiλ1640, respectively), even in extremely metal poor environments (), which could be embedding PopIII galaxies and DCBH.