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arXiv 1012.3917astro-ph.HE
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原型风吹气泡NGC 6888的朱雀观测

Suzaku Observations of the Prototype Wind-Blown Bubble NGC 6888

Svetozar A. Zhekov, Sangwook Park

摘要:

我们提出了一个分析的原型风吹气泡NGC 6888这是基于使用标准的光谱模型和理论模型与观测的直接比较朱雀观测。NGC 6888的X射线谱是软的,大多数X射线在(0.3 - 1.5 keV)能量范围内。但是,也检测到硬X射线(1.5 - 4.0 keV)(约为观测通量的10%)。相应的光谱拟合需要一个相对较冷的等离子体与kT < 0.5 keV but much hotter plasma with temperature kT >2.0 keV是需要匹配所观察到的硬X射线发射。我们发现在NGC 6888的热泡内没有明显的温度变化。导出的丰度(N,O,Ne)与光学星云的丰度一致。这表明X射线发射气体和外部冷壳层的共同起源:大多数X射线等离子体(具有不均匀的空间分布:团块)从光学星云流入热气泡。如果电子热传导是有效的,这自然可以解释大多数X射线发射等离子体的相对低的等离子体温度。或者,NGC 6888中的热气泡将是绝热的,而冷团块可能通过重粒子之间的能量交换(热离子扩散到冷团块中)被加热到X射线温度。

英文摘要:

We present an analysis of the Suzaku observations of the prototype wind-blown bubble NGC 6888 which is based both on use of standard spectral models and on a direct comparison of theoretical models with observations. The X-ray spectra of NGC 6888 are soft and most of the X-rays are in the (0.3 - 1.5 keV) energy range. But, hard X-rays (1.5 - 4.0 keV) are also detected (~10% of the observed flux). The corresponding spectral fits require a relatively cool plasma with kT < 0.5 keV but much hotter plasma with temperature kT > 2.0 keV is needed to match the observed hard X-ray emission. We find no appreciable temperature variations within the hot bubble in NGC 6888. The derived abundances (N, O, Ne) are consistent with those of the optical nebula. This indicates a common origin of the X-ray emitting gas and the outer cold shell: most of the X-ray plasma (having non-uniform spatial distribution: clumps) has flown into the hot bubble from the optical nebula. If the electron thermal conduction is efficient, this can naturally explain the relatively low plasma temperature of most of the X-ray emitting plasma. Alternatively, the hot bubble in NGC 6888 will be adiabatic and the cold clumps are heated up to X-ray temperatures likely by energy exchange between the heavy particles (hot ions diffusing into the cold clumps).

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