Photoionization in the halo of the Galaxy
Photoionization in the halo of the Galaxy
复制标题
银河系光晕中的光电离
DOI：
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发表时间：
1986
期刊：
影响因子：
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通讯作者：
J. Harrington
中科院分区：
文献类型：
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作者：
J. Bregman;J. Harrington
计算了晕中的电离辐射场，发现在13.6-45 eV的范围内，O-B星逸出盘的光占主导地位，行星状星云在45-54 eV，类星体和银河系软X射线背景在54-2000 eV，以及河外X射线背景在更高的能量。光电离模型计算与此辐射场入射在晕云的恒定密度的各种密度，正常和耗尽的丰度，并与入射光谱的变化。对于至少三次电离的物质，例如Si IV、C IV、N V和O VI，线比由具有最大体积的介入气体确定，其不一定是最大质量组分。来自双电离物种如Si III的柱密度应大于来自三电离物种的柱密度。讨论了光电离气体在宇宙线支持的晕和银河喷泉中的作用。提出了光电离模型的观测检验方法。80个参考文献。
The ionizing radiation field in the halo is calculated and found to be dominated in the 13.6-45 eV range by light from O-B stars that escapes the disk, by planetary nebulae at 45-54 eV, by quasars and the Galactic soft X-ray background at 54-2000 eV, and by the extragalactic X-ray background at higher energies. Photoionization models are calculated with this radiation field incident on halo clouds of constant density for a variety of densities, for normal and depleted abundances, and with variations of the incident spectrum. For species at least triply ionized, such as Si IV, C IV, N V, and O VI, the line ratios are determined by intervening gas with the greatest volume, which is not necessarily the greatest mass component. Column densities from doubly ionized species like Si III should be greater than from triply ionized species. The role of photoionized gas in cosmic ray-supported halos and Galactic fountains is discussed. Observational tests of photoionization models are suggested. 80 references.