论文标题
用于测量HII区域电子温度的物理动机的“电荷交换方法”
A physically motivated `charge-exchange method' for measuring electron temperatures within HII regions
论文作者
论文摘要
目的：温度不确定性困扰着我们对ISM内丰度变化的理解。使用Phangs-Muse大型程序，我们开发并应用了一种新技术，以建模〜50 PC分辨率的附近19个螺旋星系中HII区域产生的强发射线，并推断为星云的电子温度。方法：由于原子氧与氢与氢的电离分数的电荷交换耦合，因此可以将观察到的[OI] 6300/HA线比的发射率建模为气相氧丰度（O/H）的函数（O/H），离子化馏分（F_ION）和电子温度（F_ION）和电子温度（T_E）。我们使用强线金属校准测量（O/H），并确定f_ion和[SIII] 9069/[SII] 6716,6730之间的相关性，跟踪电离参数变化。结果：我们通过基于Auroral Line检测的直接测量（[NII] 5755）来求解T_E，并基于Auroral Line检测到〜600 K之内的T_E（[NII] 5755）进行测试。我们应用了将T_E计算为T_E的收费 - 交换方法，将T_E计算至19个Phangs-Muse Galaxies的4,129个HII区域。我们发现径向温度梯度，小尺度上的同质性增加以及磁盘中的方位角温度变化，与已建立的丰度模式相对应。这项用于测量电子温度的新技术利用了星系样品跨星系样品的光学整体场单位光谱图的日益增长的可用性，与直接的Auroral线检测相比，增加了可用的统计数据。
Aims: Temperature uncertainties plague our understanding of abundance variations within the ISM. Using the PHANGS-MUSE large program, we develop and apply a new technique to model the strong emission lines arising from HII regions in 19 nearby spiral galaxies at ~50 pc resolution and infer electron temperatures for the nebulae. Methods: Due to the charge-exchange coupling of the ionization fraction of the atomic oxygen to that of hydrogen, the emissivity of the observed [OI]6300/Ha line ratio can be modeled as a function of gas phase oxygen abundance (O/H), ionization fraction (f_ion) and electron temperature (T_e). We measure (O/H) using a strong line metallicity calibration, and identify a correlation between f_ion and [SIII]9069/[SII]6716,6730, tracing ionization parameter variations. Results: We solve for T_e, and test the method by reproducing direct measurements of T_e([NII]5755) based on auroral line detections to within ~600 K. We apply this charge-exchange method of calculating T_e to 4,129 HII regions across 19 PHANGS-MUSE galaxies. We uncover radial temperature gradients, increased homogeneity on small scales, and azimuthal temperature variations in the disks that correspond to established abundance patterns. This new technique for measuring electron temperatures leverages the growing availability of optical integral field unit spectroscopic maps across galaxy samples, increasing the statistics available compared to direct auroral line detections.
