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arXiv 1107.5116astro-ph.CO
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最遥远射电星系的化学性质

Chemical properties in the most distant radio galaxy

Kenta Matsuoka, Tohru Nagao, Roberto Maiolino, Alessandro Marconi, Yoshiaki Taniguchi

摘要:

本文介绍了用斯巴鲁望远镜FOCAS观测到的Z = 5.19的最远射电星系TN J 0924 -2201的深光谱。我们成功地检测到,第一次,CIV 1549发射线从窄线区(NLR)。除了发射线通量的Ly α和CIV,我们设置上限的NV和HeII排放。我们使用这些线检测和上限来约束TN J 0924 -2201的化学性质。通过将观测到的发射线通量比与光电离模型进行比较,我们推断在宇宙年龄约为1.1 Gyr时,碳与氧的相对丰度已经达到[C/O] > -0.5。这个[C/O]的下限高于星系化学演化最早阶段的预期比值,表明TN J 0924 -2201在z = 5.19时已经经历了显著的化学演化。

英文摘要:

We present a deep optical spectrum of TN J0924-2201, the most distant radio galaxy at z = 5.19, obtained with FOCAS on the Subaru Telescope. We successfully detect, for the first time, the CIV1549 emission line from the narrow-line region (NLR). In addition to the emission-line fluxes of Ly alpha and CIV, we set upper limits on the NV and HeII emissions. We use these line detections and upper limits to constrain the chemical properties of TN J0924-2201. By comparing the observed emission-line flux ratios with photoionization models, we infer that the carbon-to-oxygen relative abundance is already [C/O] > -0.5 at a cosmic age of ~ 1.1 Gyr. This lower limit on [C/O] is higher than the ratio expected at the earliest phases of the galaxy chemical evolution, indicating that TN J0924-2201 has already experienced significant chemical evolution at z = 5.19.

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