Stellar and Nebular Diagnostics in the Ultraviolet for Star-forming Galaxies
Stellar and Nebular Diagnostics in the Ultraviolet for Star-forming Galaxies
复制标题
恒星形成星系的紫外线中的恒星和星云诊断
DOI：
10.3847/1538-4357/aacd50
复制
发表时间：
2018
期刊：
影响因子：
--
通讯作者：
D. Berg
中科院分区：
文献类型：
--
作者：
N. Byler;J. Dalcanton;C. Conroy;Benjamin D. Johnson;E. Levesque;D. Berg
利用光学发射和吸收谱线来约束星系中气体的金属丰度和电离参数已有很长的历史。然而，对于紫外线（UV），可比较的诊断方法尚不完善。在这里，我们评估了紫外吸收和发射特征的诊断潜力，并根据本地和高红移星系的观测来评估诊断。我们使用Byler等人的柔性恒星群合成（FSPS）星云发射模型，扩展到包括紫外线的发射预测，以评估已建立的紫外线恒星吸收指数的金属丰度敏感性，并确定那些包括星云发射的重要贡献。我们提出了一个模型紫外发射在线通量作为金属丰度和电离参数的函数，同时假设瞬时爆发和恒定的恒星形成速率。我们确定了约束金属丰度和电离参数的强发射谱线组合，包括[C iii] λ1907， C iii] λ1909, O iii] λ1661,1666, Si iii] λ1883,1892, C iv λ1548,1551, N ii] λ1750,1752和Mg ii λ2796，并开发了经典的“Baldwin Phillips Terlevich”图的紫外版本。我们量化了恒星风发射和星云线发射对诊断谱线比率的相对贡献，其中包括C iv λ1548,1551谱线，我们还建立了N和C富集的观测驱动关系，从而提高了光电离模型的性能。我们总结了低、中、高分辨率静止紫外光谱的最佳诊断选择和相关的红移范围，为詹姆斯·韦伯太空望远镜的发射做准备。
There is a long history of using optical emission and absorption lines to constrain the metallicity and ionization parameters of gas in galaxies. However, comparable diagnostics are less well developed for the ultraviolet (UV). Here, we assess the diagnostic potential of both absorption and emission features in the UV and evaluate the diagnostics against observations of local and high-redshift galaxies. We use the Flexible Stellar Population Synthesis (FSPS) nebular emission model of Byler et al., extended to include emission predictions in the UV, to evaluate the metallicity sensitivity of established UV stellar absorption indices and to identify those that include a significant contribution from nebular emission. We present model UV emission-line fluxes as a function of metallicity and ionization parameter, assuming both instantaneous bursts and constant star formation rates. We identify combinations of strong emission lines that constrain metallicity and ionization parameters, including [C iii] λ1907, C iii] λ1909, O iii] λ1661,1666, Si iii] λ1883,1892, C iv λ1548,1551, N ii] λ1750,1752, and Mg ii λ2796, and we develop UV versions of the canonical “Baldwin Phillips Terlevich” diagram. We quantify the relative contribution from stellar wind emission and nebular line emission to diagnostic line ratios that include the C iv λ1548,1551 lines, and we also develop an observationally motivated relationship for N and C enrichment that improves the performance of photoionization models. We summarize the best diagnostic choices and the associated redshift range for low-, mid-, and high-resolution rest-UV spectroscopy in preparation for the launch of the James Webb Space Telescope.
影响因子：
56.9
作者：
H. Sana;S. D. Mink;A. D. Koter;N. Langer;C. Evans;M. Gieles;E. Gosset;R. Izzard;J. L. Bouquin-J.
通讯作者：
H. Sana;S. D. Mink;A. D. Koter;N. Langer;C. Evans;M. Gieles;E. Gosset;R. Izzard;J. L. Bouquin-J.