The O3N2 and N2 abundance indicators revisited: improved calibrations based on CALIFA and T e-based literature data
The O3N2 and N2 abundance indicators revisited: improved calibrations based on CALIFA and T e-based literature data
复制标题
DOI：
10.1051/0004-6361/201321956
复制
发表时间：
2013-07
影响因子：
6.5
通讯作者：
R. Marino;F. Rosales-Ortega;S. Sánchez;A. Paz;J. Vílchez;D. Miralles-Caballero;C. Kehrig;E. Pére
中科院分区：
文献类型：
--
作者：
R. Marino;F. Rosales-Ortega;S. Sánchez;A. Paz;J. Vílchez;D. Miralles-Caballero;C. Kehrig;E. Pére
积分场光谱学的使用是因为最近允许测量越来越多的恒星形成星系的发射线通量，在本地和高红移。许多研究已经使用这些通量来推导星系的气相金属丰度，通过应用所谓的强线方法。然而，这些数据集使用的金属丰度指标是使用很少的直接丰度数据点（基于T_e的测量）进行经验校准的。此外，在这些校准中通常缺乏对这些指标的预测区间的精确确定。这种限制可能会导致在确定气相金属丰度时产生系统性误差，特别是在高红移时，这可能会对我们对宇宙化学演化的理解产生强烈影响。本研究的主要目标是审查最广泛使用的经验氧校准，O3 N2和N2，通过使用新的直接丰度测量。我们特别注意（1）这些校准的预期不确定性作为指数值或丰度的函数，（2）可能存在的系统偏移。这是可能的，这要归功于对迄今为止基于T_e的H II区域的最雄心勃勃的汇编的分析。这个新的数据集汇编了从文献中提取的603个H II区域的Te丰度，但也包括来自CALIFA调查的新测量值。除了提供新的和改进的经验校准的气体丰度，我们还提出了一个比较我们的重新校准与共3423额外的CALIFA H II复合物的丰度来自使用ONS校准从文献中。基于T_e和ONS丰度的组合分析使我们能够在所有统计显著性、质量和参数空间覆盖范围方面获得迄今为止O3 N2和N2单比率指标的最准确校准。特别是，我们推断，这些指标显示较浅的丰度依赖性和统计上显着的偏移相比，其他的。O3 N2和N2指示剂可凭经验应用于从分别具有0.18和0.16的随机误差的直接丰度测定或从间接丰度测定导出氧丰度校准（但基于大量数据），达到平均精度0.08和0.09dex（随机）和0.02和0.08dex（系统的;与直接估计相比）。
The use of integral field spectroscopy is since recently allowing to measure the emission line fluxes of an increasingly large number of star-forming galaxies, both locally and at high redshift. Many studies have used these fluxes to derive the gas-phase metallicity of the galaxies by applying the so-called strong-line methods. However, the metallicity indicators that these datasets use were empirically calibrated using few direct abundance data points (T_e-based measurements). Furthermore, a precise determination of the prediction intervals of these indicators is commonly lacking in these calibrations. Such limitations might lead to systematic errors in determining the gas-phase metallicity, especially at high redshift, which might have a strong impact on our understanding of the chemical evolution of the Universe. The main goal of this study is to review the most widely used empirical oxygen calibrations, O3N2 and N2, by using new direct abundance measurements. We pay special attention to (1) the expected uncertainty of these calibrations as a function of the index value or abundance derived and (2) the presence of possible systematic offsets. This is possible thanks to the analysis of the most ambitious compilation of T_e-based H II regions to date. This new dataset compiles the Te-based abundances of 603 H II regions extracted from the literature but also includes new measurements from the CALIFA survey. Besides providing new and improved empirical calibrations for the gas abundance, we also present a comparison between our revisited calibrations with a total of 3423 additional CALIFA H II complexes with abundances derived using the ONS calibration from the literature. The combined analysis of T_e-based and ONS abundances allows us to derive their most accurate calibration to date for both the O3N2 and N2 single-ratio indicators, in terms of all statistical significance, quality, and coverage of the parameters space. In particular, we infer that these indicators show shallower abundance dependencies and statistically significant offsets compared to others'. The O3N2 and N2 indicators can be empirically applied to derive oxygen abundances calibrations from either direct abundance determinations with random errors of 0.18 and 0.16, respectively, or from indirect ones (but based on a large amount of data), reaching an average precision of 0.08 and 0.09 dex (random) and 0.02 and 0.08 dex (systematic; compared to the direct estimations), respectively.