The Nature of Unresolved Soft X-Ray Emission from the Galactic Disk
The Nature of Unresolved Soft X-Ray Emission from the Galactic Disk
复制标题
DOI：
10.1093/pasj/61.sp1.s115
复制
发表时间：
2008-10
影响因子：
2.3
通讯作者：
K. Masui;K. Mitsuda;N. Yamasaki;Y. Takei;S. Kimura;T. Yoshino;D. McCammon
中科院分区：
文献类型：
--
作者：
K. Masui;K. Mitsuda;N. Yamasaki;Y. Takei;S. Kimura;T. Yoshino;D. McCammon
虽然大约40%的软X射线背景辐射在0.4至1 keV的范围内有河外的起源，因此完全被银河系的吸收在中平面方向上，它最多减少约20%。朱雀观测的方向，（`，B）=（235 i，0 i），显示了O VII K射线发射强度与朱雀观测的MBM-12云，但揭示了一个狭窄的隆起峰值为0.9 keV。后一个分量部分地填补了中平面河外分量的减少。该特征可以很好地由具有约0.8keV的温度的薄的热发射来表示。由于在空间上扩展的热气体隐含着高压，因此发射很可能是未解决的微弱源的总和。我们认为很大一部分的发射来自暗淡的dM星。我们构建了一个模型光谱的空间未分辨的dM星，一贯解释所观察到的光谱和表面亮度。该模型还表明，dM星的辐射随着B的增加而迅速减少，因此它不能完全补偿B 2 i-10 i处河外分量的减少。
Although about 40% of the soft X-ray background emission in 0.4 to 1 keV range has extragalactic origins and thus is totally blocked by the galactic absorption in midplane directions, it decreases at most by about 20% in midplane. Suzaku observation of the direction, (`, b) = (235 i ,0 i ), showed an O VII K˛ emission intensity comparable with that of the MBM-12 on cloud Suzaku observation, but revealed a narrow bump peaked at � 0.9 keV. The latter component is partly filling the decrease of the extragalactic component in midplane. The feature can be well represented by a thin thermal emission with a temperature of about 0.8 keV. Because of the high pressure implied for spatially extended hot gas, the emission is likely a sum of unresolved faint sources. We consider a large fraction of the emission originates from faint dM stars. We constructed a model spectrum for spatially unresolved dM stars that consistently explains the observed spectrum and the surface brightness. The model also suggests that the emission from dM stars decreases very rapidly with increasing b, and thus that it cannot compensate entirely the decrease of the extragalactic component at b � 2 i -10 i .