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arXiv 1307.5950astro-ph.CO
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\HII区新的强谱线畸变诊断：$κ$分布电子能量的影响和新的原子数据

New Strong Line Abundance Diagnostics for \HII Regions: Effects of $κ$-Distributed Electron Energies and New Atomic Data

Michael A. Dopita, Ralph S. Sutherland, David C. Nicholls, Lisa J. Kewley, Frédéric P. A. Vogt

备注：
Accepted for Astrophysical Journal Supplement Series, 106pp, 32 figs
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摘要：

最近，\citet{Nicholls12}受到太阳系天体物理等离子体的\emph{in situ}观测的启发，提出了在\HII区域的电子的特征是电子能量的$κ$分布，而不是简单的麦克斯韦-玻尔兹曼分布。在这里，我们已经收集了新的原子数据在一个修改后的光电离代码，探索新的原子数据和$κ$ -分布的影响，用于确定化学丰度的强线技术在\HII地区。通过比较复合温度（$T_{\rm rec}$）和禁带温度（$T_{\rm FL}$），我们得出结论：$ κ\sim 20$。虽然只代表一个轻微的偏离平衡，这是足以强烈影响使用的方法，取决于从禁线的电子温度的测量确定的丰度。我们提出了一些新的发射线比诊断，干净地分离的两个参数，确定光谱的\HII区域-电离参数$q$或$\cal{U}$和化学丰度; 12+log（O/H）。一个自动化的代码来提取这些参数。使用来自\citet{vanZee98}的同质数据集，我们发现所有这些不同诊断之间的自洽结果。不同线比诊断之间的系统误差比在早期的强线工作中发现的要小得多。总的来说，$κ$ -分布对仅基于理论模型得出的强线丰度的影响相当小。

英文摘要：

Recently, \citet{Nicholls12}, inspired by \emph{in situ} observations of solar system astrophysical plasmas, suggested that the electrons in \HII regions are characterised by a $κ$-distribution of electron energies rather than by a simple Maxwell-Boltzmann distribution. Here we have collected together the new atomic data within a modified photoionisation code to explore the effects of both the new atomic data and the $κ$-distribution on the strong-line techniques used to determine chemical abundances in \HII regions. By comparing the recombination temperatures ($T_{\rm rec}$) with the forbidden line temperatures ($T_{\rm FL}$) we conclude that $ κ\sim 20$. While representing only a mild deviation from equilibrium, this is sufficient to strongly influence abundances determined using methods which depend on measurements of the electron temperature from forbidden lines. We present a number of new emission line ratio diagnostics which cleanly separate the two parameters determining the optical spectrum of \HII regions - the ionisation parameter $q$ or $\cal{U}$ and the chemical abundance; 12+log(O/H). An automated code to extract these parameters is presented. Using the homogeneous dataset from \citet{vanZee98}, we find self-consistent results between all these different diagnostics. The systematic errors between different line ratio diagnostics are much smaller than was found in the earlier strong line work. Overall the effect of the $κ$-distribution on the strong line abundances derived solely on the basis of theoretical models is rather small.

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