论文标题
星形星系中的紫外线和光学金属度的比较
A comparison of UV and optical metallicities in star-forming galaxies
论文作者
论文摘要
我们在最早的星系中研究星际介质（ISM）的性质的能力将依赖于静止型紫外线（UV）波长的发射线诊断。在这项工作中，我们使用紫外线排放线确定对金属性敏感的诊断。我们使用带有REST框架紫外线和光谱的星系样品将紫外线衍生的金属性与标准的，完善的光学金属度进行了比较。我们发现HE2-O3C3诊断（He II 1640 / C III 1906,1909 vs. O III 1666 / C III 1906,1909）是一种可靠的金属性示踪剂，尤其是在低金属性（12+log（o / h）<8）的情况下，在那里贡献了Stellar的贡献。我们发现SI3-O3C3诊断（SI III 1883 / C III 1906,1909与O III 1666 / C III 1666 / C III 1906，1909）是一个可靠的金属示踪剂，尽管散布较大（0.2-0.3 DEX），我们建议这是由加油量的变异驱动的。我们发现C4-O3C3诊断（C IV 1548,1550 / O III 1666 vs. O III 1666 / C III 1906，1909）与光学衍生的金属率较差。我们讨论了这些差异金属性确定的可能解释，包括电离光谱的硬度，恒星风发射的贡献以及非微量尺度的气相丰度。最后，我们提供了两个新的UV氧丰度诊断，从HE2-O3C3和SI3-O3C3图中的多项式拟合到模型网格表面计算出来。
Our ability to study the properties of the interstellar medium (ISM) in the earliest galaxies will rely on emission line diagnostics at rest-frame ultraviolet (UV) wavelengths. In this work, we identify metallicity-sensitive diagnostics using UV emission lines. We compare UV-derived metallicities with standard, well-established optical metallicities using a sample of galaxies with rest-frame UV and optical spectroscopy. We find that the He2-O3C3 diagnostic (He II 1640 / C III 1906,1909 vs. O III 1666 / C III 1906,1909) is a reliable metallicity tracer, particularly at low metallicity (12+log(O/H) < 8), where stellar contributions are minimal. We find that the Si3-O3C3 diagnostic (Si III 1883 / C III 1906,1909 vs. O III 1666 / C III 1906,1909) is a reliable metallicity tracer, though with large scatter (0.2-0.3 dex), which we suggest is driven by variations in gas-phase abundances. We find that the C4-O3C3 diagnostic (C IV 1548,1550 / O III 1666 vs. O III 1666 / C III 1906,1909) correlates poorly with optically-derived metallicities. We discuss possible explanations for these discrepant metallicity determinations, including the hardness of the ionizing spectrum, contribution from stellar wind emission, and non-solar-scaled gas-phase abundances. Finally, we provide two new UV oxygen abundance diagnostics, calculated from polynomial fits to the model grid surface in the He2-O3C3 and Si3-O3C3 diagrams.
