Discovery of 6.4 keV line and soft X-ray emissions from G323.7-1.0 with Suzaku
Discovery of 6.4 keV line and soft X-ray emissions from G323.7-1.0 with Suzaku
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使用朱雀发现 G323.7-1.0 的 6.4 keV 谱线和软 X 射线发射
DOI：
10.1093/pasj/psx158
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发表时间：
2018
影响因子：
2.3
通讯作者：
Katsuji
中科院分区：
文献类型：
--
作者：
Saji;Shigetaka; Matsumoto;Hironori; Nobukawa;Masayoshi; Nobukawa;Kumiko K.; Uchiyama;Hideki; Yamauchi;Shigeo; Koyama;Katsuji
本文分析了银河系超新星遗迹（SNR）候选者G323.7−1.0的Suzaku x射线数据，以寻找x射线辐射。6.4 keV线和软x射线的空间扩展增强在无线电外壳内部或上面发现。软x射线增强将是沿射电壳层发射的类壳x射线中最热的部分。在4.1 σ的显著性水平上检测到6.4 keV线增强。等效宽度（EW）下限为1.2 keV。6.4 keV线的能量质心为6.40±0.04 keV，表明铁的电离程度低于类ne态。如果6.4 keV线来自电离非平衡热等离子体，则需要在低电离状态下存在富铁喷射物，这是相对较老的信噪比所不利的。6.4 keV线的增强可能是由于高能粒子在密集的星际介质中使铁原子发生k壳电离。由于没有照射的x射线源，6.4 keV线增强的起源不可能是光电离。大电子战只能用能量为~ 10 MeV的宇宙射线质子产生的k壳电离来解释，这可能是由G323.7−1.0的激波加速度产生的。
In this paper, the Suzaku X-ray data of the Galactic supernova remnant (SNR) candidate G323.7−1.0 are analyzed to search for X-ray emissions. Spatially extended enhancements in the 6.4 keV line and in soft X-rays are found inside or on the radio shell. The soft X-ray enhancement would be the hottest part of the shell-like X-ray emission along the radio shell. The 6.4 keV line enhancement is detected at a significance level of 4.1 σ. The lower limit of the equivalent width (EW) is 1.2 keV. The energy centroid of the 6.4 keV line is 6.40 ± 0.04 keV, indicating that the iron is less ionized than the Ne-like state. If the 6.4 keV line originates from ionizing non-equilibrium thermal plasma, presence of iron-rich ejecta in a low-ionization state is required, which is disfavored by the relatively old age of the SNR. The 6.4 keV line enhancement would be due to K-shell ionization of iron atoms in a dense interstellar medium by high-energy particles. Since there is no irradiating X-ray source, the origin of the 6.4 keV line enhancement is not likely the photoionization. The large EW can only be explained by K-shell ionization due to cosmic-ray protons with an energy of ∼10 MeV, which might be generated by the shock acceleration in G323.7−1.0.