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arXiv 0802.2943astro-ph
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用XMM-牛顿法对M82的深部X射线观测

A deep X-ray observation of M82 with XMM-Newton

Piero Ranalli, Andrea Comastri, Livia Origlia, Roberto Maiolino

摘要:

我们报告的分析深(100 ks)观测的星爆星系M82的EPIC和RGS仪器上的X射线望远镜XMM-牛顿。宽带(0.5-10 keV)发射是由于至少三个光谱分量:i)来自点源的连续谱发射; ii)来自热气体的热等离子体发射; iii)来自中性金属(Mg和Si)的电荷交换发射。等离子体发射具有双峰差分发射测量,峰值在~0.5 keV和~7 keV。空间分辨光谱表明,化学绝对丰度在外流中并不均匀分布,而是在外围较大,靠近星系中心较小。丰度比也显示出空间变化。从X射线得到的氧丰度比在红超巨星大气中测得的要低,这导致了一种假设,即很大一部分氧离子已经冷却,不再发射能量> 0.5 keV的氧离子。

英文摘要:

We report on the analysis of a deep (100 ks) observation of the starburst galaxy M82 with the EPIC and RGS instruments on board the X-ray telescope XMM-Newton. The broad-band (0.5-10 keV) emission is due to at least three spectral components: i) continuum emission from point sources; ii) thermal plasma emission from hot gas; iii) charge exchange emission from neutral metals (Mg and Si). The plasma emission has a double-peaked differential emission measure, with the peaks at ~0.5 keV and ~7 keV. Spatially resolved spectroscopy has shown that the chemical absolute abundances are not uniformly distributed in the outflow, but are larger in the outskirts and smaller close to the galaxy centre. The abundance ratios also show spatial variations. The X-ray derived Oxygen abundance is lower than that measured in the atmospheres of red supergiant stars, leading to the hypothesis that a significant fraction of Oxygen ions have already cooled off and no longer emit at energies > ~0.5 keV.

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