CECILIA：利用灵活的光电离模型在无极光发射线条件下精确测量元素丰度
CECILIA: Using Flexible Photoionization Models to Accurately Measure Abundances without Auroral Lines
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中文总结 AI 辅助
本研究利用CECILIA巡天数据，验证新型光电离建模代码Cue在无极光发射线条件下，通过常规发射线准确测量星系金属丰度的可行性，并探讨其偏差与最佳实践。
中文摘要 AI 辅助
JWST促进了在高红移星系中直接测量电子温度和元素丰度所需的微弱极光发射线的探测。然而，此类测量仍需要大量的观测投入，这可能使得在宇宙多个时期进行基于直接方法的金属丰度标度关系的自洽群体研究变得极其昂贵。光电离建模可以让我们利用更常规观测到的发射线，在具有更浅光谱的更大星系样本中测量金属丰度。我们使用来自CECILIA巡天的$z\sim 2$星系以及来自LBT $Y_P$项目的本地星系和H II区，将通过$T_e$方法获得的丰度测量结果与使用新型光电离建模代码Cue估算的丰度进行比较。基于这些结果，我们探讨了利用光电离建模测量气体相位金属丰度的可行性、引入的偏差以及最佳实践。我们表明，Cue可以在不依赖电离光谱的情况下准确测量O/H，并且通过相对明亮的氧和硫发射线即可实现O/H的准确恢复，这表明Cue可用于测量缺乏直接测量O/H所需深度的大样本中的金属丰度。然而，在高红移星系中，使用硫发射线也可能严重偏差光电离建模的结果，这些星系中非太阳丰度模式很常见。我们就使用光电离模型测量本地和高红移样本中的金属丰度提出建议，并展望了光电离建模方法的未来发展。
英文摘要
JWST has facilitated the detection of faint, auroral emission lines needed to directly measure the electron temperature and elemental abundances in high-redshift galaxies. However, such measurements still require substantial observational investment, potentially making self-consistent, population-level studies of direct-method metallicity scaling relations across multiple epochs of Cosmic time prohibitively expensive. Photoionization modeling could allow us to measure metallicity using more routinely-observed emission lines across larger galaxy samples with shallower spectra. We use $z\sim 2$ galaxies from the CECILIA survey and local galaxies and H II regions from the LBT $Y_P$ Project to compare abundance measurements made via the $T_e$ method to abundances estimated using the novel photoionization modeling code, Cue. Based on the results, we explore the viability of, biases introduced by, and the best practices for measuring gas-phase metallicity with photoionization modeling. We show that Cue can be used to accurately measure O/H while remaining agnostic to the ionizing spectrum and that accurate recovery of O/H can be achieved with relatively bright oxygen and sulfur lines, demonstrating that Cue could be used to measure metallicity in large samples that lack the depth necessary for direct measurements of O/H. However, using sulfur emission lines can also severely bias the results of photoionization modeling in high-redshift galaxies, where non-Solar abundance patterns are common. We make recommendations regarding the use of photoionization models to measure metallicity in local and high-redshift samples and future developments to photoionization modeling methods.
发表机构
- Northwestern University（西北大学）
- Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA)（天体物理学跨学科探索与研究中心）
- The Observatories of the Carnegie Institution for Sciences（卡内基科学研究所天文台）
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