用XMM-牛顿天文台观测天鹅座环西南区的等离子体结构
The Plasma Structure of the Southwestern Region of the Cygnus Loop with the XMM-Newton Observatory
摘要：
我们用\textit{XMM-Newton}在两个点上观测了天鹅座圈的西南区域。观察到的区域被称为“井喷”区域，该区域在南部进一步延伸。“爆发”的起源还不太清楚，但在射电观测中，有人认为这里还有另一颗超新星遗迹。为了研究该区域在X射线中的详细结构，我们将视场划分为33个盒状区域。用双组分非平衡电离模型对光谱进行了拟合。重元素的排放量分布从环的内部区域到外部区域逐渐减小。然后，我们也将我们的视野划分为26个环形扇区来研究径向等离子体结构。从获得的金属丰度来看，这与X射线发射是天鹅座环起源的观点一致，我们得出结论，高$kT_{e}$分量（$\sim$ 0.4 keV）来自喷出物，而低$kT_{e}$分量（$\sim$ 0.2 keV）来自上扫的星际介质。低$kT_{e}$组分的通量远小于高$kT_{e}$组分的通量，表明ISM组分非常薄。此外，喷出物成分的相对丰度显示出类似的值从天鹅座圈以前的观测。我们在X射线中没有发现任何证据表明“爆发”区域的性质起源于额外的超新星遗迹。根据喷出物的成分，我们计算了各种金属的质量，并估计天鹅座圈的起源是核心坍塌爆炸，而不是Ia型超新星。
英文摘要：
We observed the southwestern region of the Cygnus Loop in two pointings with \textit{XMM-Newton}. The region observed is called the "blow-out" region that is extended further in the south. The origin of the "blow-out" is not well understood while it is suggested that there is another supernova remnant here in radio observation. To investigate the detail structure of this region in X-ray, we divided our fields of view into 33 box regions. The spectra are well fitted by a two-component nonequilibrium ionization model. The emission measure distributions of heavy elements decrease from the inner region to the outer region of the Loop. Then, we also divided our fields of view into 26 annular sectors to examine the radial plasma structure. Judging from metal abundances obtained, it is consistent with that the X-ray emission is the Cygnus Loop origin and we concluded that high-$kT_{e}$ component ($\sim$0.4 keV) originates from the ejecta while low-$kT_{e}$ component ($\sim$0.2 keV) is derived from the swept-up interstellar medium. The flux of low-$kT_{e}$ component is much less than that of high-$kT_{e}$ component, suggesting the ISM component is very thin. Also, the relative abundances in the ejecta component shows similar values to those obtained from previous observations of the Cygnus Loop. We find no evidence in X-ray that the nature of the "blow-out" region originated from the extra supernova remnant. From the ejecta component, we calculated the masses for various metals and estimated the origin of the Cygnus Loop as the core-collapse explosion rather than the Type Ia supernova.
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