ASTRID模拟中H II区的理论发射线与金属丰度定标
Theoretical emission lines and metallicity calibrations of H II regions in ASTRID simulation
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中文总结 AI 辅助
该研究基于ASTRID模拟，构建自洽预测电离参数等的理论框架，推导z=2-7星系的发射线与金属丰度定标关系，为JWST光谱解释及化学演化追踪提供实用方案。
中文摘要 AI 辅助
我们提出了一个理论框架，用于推导红移z=2-7星系的红移依赖型金属丰度定标关系。在该方法中，电离参数（U）和气体压力（P）并非预先假设，而是自洽预测得出。通过将ASTRID宇宙学模拟与恒星种群合成（SPS）及MAPPINGS V光电离建模相结合，我们在解析风驱动气泡模型下演化年轻星团，该模型将恒星反馈直接与局部星际介质（ISM）密度耦合，使H II区属性由基础物理过程自然涌现，而非作为自由参数处理。发射线预测经观测恒星形成率指标（偏差<0.05 dex）和[O III]光度函数验证。我们推导了常见光学（如R23、O3N2、N2、O32）及紫外（如C3O3、N3O3）诊断的定标关系，发现这些关系存在显著红移演化，主要由电离条件变化驱动。贝叶斯分析量化了不同信噪比下的定标性能，可根据红移和数据质量给出诊断建议。在本模型中，R23定标在所有红移下表现良好且误差最小，而基于氮和碳的定标对丰度富集过程高度敏感，需谨慎使用。这些结果为解释詹姆斯·韦布空间望远镜（JWST）光谱及追踪从宇宙正午到再电离时期的化学演化提供了实用框架。
英文摘要
We present a theoretical framework to derive redshift-dependent metallicity calibrations for galaxies at $z$=2-7. The ionization parameter ($U$) and gas pressure ($P$) in our approach are not assumed, but are predicted self-consistently. By combining the ASTRID cosmological simulation with stellar population synthesis (SPS) and MAPPINGS V photoionization modeling, we evolve young star clusters under an analytic wind-driven bubble model. This directly couples stellar feedback to the local ISM density, allowing \hii{} region properties to emerge from the underlying physics rather than being treated as free parameters. The emission-line predictions are validated against observed star-formation rate indicators (deviation <0.05 dex) and the \oiii{} luminosity function. We derive calibrations for common optical (e.g. R23, O3N2, N2, O32) and UV (e.g. C3O3, N3O3) diagnostics. We find significant redshift evolution in these relations, driven primarily by changing ionization conditions. A Bayesian analysis quantifies calibration performance under varying signal-to-noise, enabling diagnostic recommendations as a function of redshift and data quality. The R23 calibration performs well at all redshifts with minimal error in our model, while nitrogen- and carbon-based calibrations are highly sensitive to the abundance enrichment process and should be used with caution. These results provide a practical framework for interpreting JWST spectroscopy and tracing chemical evolution from cosmic noon to the epoch of reionization.
