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首页> 外文期刊>The Astrophysical journal >FAR ULTRAVIOLET SPECTROSCOPIC EXPLORER OBSERVATIONS OF O Ⅵ ABSORPTION IN THE GALACTIC HALO
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FAR ULTRAVIOLET SPECTROSCOPIC EXPLORER OBSERVATIONS OF O Ⅵ ABSORPTION IN THE GALACTIC HALO

机译：银盐晕中OⅥ吸收的远紫外分光光探测器

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摘要

Far-ultraviolet spectra of 11 active galactic nuclei observed by Far Ultraviolet Spectroscopic Explorer (FUSE) are analyzed to obtain measures of O Ⅵ λ1031.93 absorption occurring over very long paths through Milky Way halo gas. Strong O Ⅵ absorption is detected along 10 of 11 sight lines. Values of log [N(O Ⅵ) sin |b|] range from 13.80 to 14.64, with a median value of 14.21. The observations reveal the existence of a widespread but irregular distribution of O Ⅵ in the Milky Way halo. Combined with estimates of the O Ⅵ midplane density, n_0 = 2 x 10~(-8) cm~(-3), from the Copernicus satellite, the FUSE observations imply an O Ⅵ exponential scale height of 2.7 ± 0.4 kpc. We find that N(C Ⅳ)/N(O Ⅵ) ranges from ～0.15 in the disk to ～0.6 along four extragalactic sight lines. The changing ionization state of the gas from the disk to the halo is consistent with a systematic decrease in the scale heights of Si Ⅳ, C Ⅳ, N Ⅴ, to O Ⅵ from ～5.1 to ～2.7 kpc. While conductive heating models can account for the highly ionized atoms at low |z|, a combination of models (and processes) appears to be required to explain the highly ionized atoms found in the halo. The greater scale heights of Si Ⅳ and C Ⅳ compared to O Ⅵ suggests that some of the Si Ⅳ and C Ⅳ in the halo is produced in turbulent mixing layers or by photoionization by hot halo stars or the extragalactic background.
机译：分析了通过远紫外光谱浏览器（FUSE）观测到的11个活跃银河原子核的远紫外光谱，从而获得了在很长的路径上通过银河系卤气发生的OⅥλ1031.93吸收的量度。沿11个视线中的10个视线检测到强烈的OⅥ吸收。 log [N（OⅥ）sin | b |]的值范围为13.80至14.64，中值为14.21。观测结果表明，银河系光环中存在OⅥ的广泛分布，但分布不规则。结合哥白尼卫星对OⅥ中平面密度的估计值n_0 = 2 x 10〜（-8）cm〜（-3），FUSE观测表明OⅥ指数尺度高度为2.7±0.4 kpc。我们发现，N（CⅣ）/ N（OⅥ）沿着四个银河外视线从圆盘中的〜0.15到〜0.6。气体从圆盘到晕的变化电离状态与SiⅣ，CⅣ，NⅤ到OⅥ的水垢高度从〜5.1到〜2.7 kpc的系统减小是一致的。虽然传导加热模型可以解释在低| z |下高度电离的原子，但是似乎需要模型（和过程）的组合来解释在光晕中发现的高度电离的原子。与OⅥ相比，SiⅣ和CⅣ的标度高度更大，表明晕圈中的某些SiⅣ和CⅣ是在湍流混合层中产生的，或者是由热的晕圈星或银河外背景通过电离而产生的。

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