Origin of the low-temperature plasma in the Galactic center X-ray emission
Origin of the low-temperature plasma in the Galactic center X-ray emission
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银心低温等离子体的起源 X 射线发射
DOI：
10.1093/pasj/psy077
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Katsuji
中科院分区：
文献类型：
--
作者：
Yamauchi;Shigeo; Shimizu;Miku; Nobukawa;Masayoshi; Nobukawa;Kumiko K.; Uchiyama;Hideki; Koyama;Katsuji
银河系中心X射线辐射（GCXE）由高温（17 keV）和低温（11 keV）等离子体（分别为HTP和LTP）组成。HTP的全球结构在银河系中心（GC）区域大致是均匀的，HTP的起源已经被广泛研究。另一方面，长时程增强现象更为复杂，其起源尚未得到详细研究。在SxvHeα线图中，可以看到一对角状的软漫射源，它们位于相对于人马座A的对称位置。这对的X射线光谱可以用吸收的薄热等离子体模型很好地表示，温度和NH分别为0.6-0.7 keV和4 × 1022 cm −2。NH值表明该对位于GC附近。因此，这对双星的动力学时间尺度为105 yr。SxvHeα谱带的Si、S丰度和表面亮度分别为0.7-1.2和0.6-1.3太阳能，（2.0-2.4）× 10− 15 ergs −1cm−2arcmin−2。温度、丰度和表面亮度与GCXE中的LTP相似，而丰度则远大于已知的点源，通常是日冕活动星和RS CVn型活动双星。在此基础上，讨论了LTP的可能起源。
The Galactic Center X-ray emission (GCXE) is composed of high-temperature (∼7 keV) and low-temperature (∼1 keV) plasmas (HTP and LTP, respectively). The global structure of the HTP is roughly uniform over the Galactic Center (GC) region, and the origin of the HTP has been extensively studied. On the other hand, the LTP is more clumpy, and its origin has not been studied in detail. In the SxvHeα line map, a pair of horn-like soft diffuse sources are seen at symmetric positions with respect to Sagittarius A⋆. The X-ray spectra of the pair are well represented by an absorbed thin thermal plasma model of temperature andNHof 0.6–0.7 keV and 4 × 1022cm−2, respectively. TheNHvalues indicate that the pair are located near the GC. Then the dynamical time scales of the pair are ∼105yr. The Si and S abundances and the surface brightnesses in the SxvHeα line band are 0.7–1.2 and 0.6–1.3 solar, and (2.0–2.4) × 10−15erg s−1cm−2arcmin−2, respectively. The temperature, abundances, and surface brightness are similar to those of the LTP in the GCXE, while the abundances are far larger than those of known point sources, typically coronal active stars and RS CVn-type active binaries. Based on these results, the possible origin of the LTP is discussed.