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arXiv 1106.2665astro-ph.HE
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年轻大质量星系团Westerlund 1核心的漫射热X射线发射

Diffuse Thermal X-Ray Emission in the Core of the Young Massive Cluster Westerlund 1

P. J. Kavanagh, L. Norci, E. J. A. Meurs

摘要:

本文利用48 ksXMM-牛顿观测数据分析了年轻大质量星系团Westerlund 1核心的弥散硬X射线辐射。钱德拉的扩散X射线发射的结果表明,一个软的热成分与一个硬的成分,可以是热或非热。我们试图解决这种模糊性的硬组件利用较高的灵敏度XMM-牛顿扩散发射。我们的新的X射线光谱从中心(2'半径)的扩散发射被发现表现出He类Fe 6.7 keV线发射,表明在集群核心的硬发射主要是热起源。这个硬组分的潜在来源进行了审查,即一个未解决的前主序星人口,热化的集群风和超新星遗迹与恒星风的相互作用。我们发现,热化集群风可能贡献了大部分的硬排放与一些贡献的前主序星人口。超新星遗迹不太可能对当前时期的Wd 1扩散辐射有重大贡献。

英文摘要:

We present an analysis of the diffuse hard X-ray emission in the core of the young massive Galactic cluster Westerlund 1 based on a 48 ks XMM-Newton observation. Chandra results for the diffuse X-ray emission have indicated a soft thermal component together with a hard component that could be either thermal or non-thermal. We seek to resolve this ambiguity regarding the hard component exploiting the higher sensitivity of XMM-Newton to diffuse emission. Our new X-ray spectra from the central (2' radius) diffuse emission are found to exhibit He-like Fe 6.7 keV line emission, demonstrating that the hard emission in the cluster core is predominantly thermal in origin. Potential sources of this hard component are reviewed, namely an unresolved Pre-Main Sequence population, a thermalized cluster wind and Supernova Remnants interacting with stellar winds. We find that the thermalized cluster wind likely contributes the majority of the hard emission with some contribution from the Pre-Main Sequence population. It is unlikely that Supernova Remnants are contributing significantly to the Wd1 diffuse emission at the current epoch.

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