Number density distribution of near-infrared sources on a sub-degree scale in the Galactic center: Comparison with the Fe XXV Kα line at 6.7 keV
Number density distribution of near-infrared sources on a sub-degree scale in the Galactic center: Comparison with the Fe XXV Kα line at 6.7 keV
复制标题
银心亚度尺度近红外源数密度分布：与 6.7 keV 的 Fe XXV Kα 线比较
DOI：
10.1093/pasj/psv100
复制
发表时间：
2015
影响因子：
2.3
通讯作者：
T. et al.（12名中8番目）
中科院分区：
文献类型：
--
作者：
Yasui;K.; Nishiyama;S.; Yoshikawa;T. et al.（12名中8番目）
将我们银河系中心区域的 H 和 KS 波段勘测得出的恒星分布与朱雀卫星观测到的 FexxvKα (6.7 keV) 线强度进行比较。此次勘测针对的是银河系坐标 |l| ≲ 30 和 |b| ≲ 10（R⊙= 8 kpc时相当于0.8 kpc × 0.3 kpc），利用消光校正星等KS,0= 10.5推导出恒星数密度分布N(KS,0;l,b)。这个深度足以探测古老的红巨星族，进而估计微弱 X 射线点源（例如日冕活跃双星和灾难变量）的 (l,b) 分布。在银道面（b= 0°）内，N(10.5;l,b)在-01≥l≥-07范围内向银心方向增加|l|-0.30±0.03，但这种增加明显慢于FexxvKα线强度的增加（|l|-0.44±0.02）。如果使用外部区域中的比率进行归一化 15 ≤ |l| ≤ 28，其中微弱的 X 射线点源被认为主导了漫射银河 X 射线脊发射，FexxvKα 线强度超过恒星数密度的部分在 |l| 处至少是两倍= 01。这表明银河系中心漫射发射的很大一部分来自真正漫射的光学薄热等离子体，而不是来自与旧恒星群相关的微弱 X 射线点源的未解析集合。
The stellar distribution derived from anH- andKS-band survey of the central region of our Galaxy is compared with the FexxvKα (6.7 keV) line intensity observed with the Suzaku satellite. The survey is for the galactic coordinates |l| ≲ 30 and |b| ≲ 10 (equivalent to 0.8 kpc × 0.3 kpc forR⊙= 8 kpc), and the number-density distributionN(KS,0;l,b) of stars is derived by using the extinction-corrected magnitudeKS,0= 10.5. This is deep enough to probe the old red-giant population and in turn to estimate the (l,b) distribution of faint X-ray point sources such as coronally active binaries and cataclysmic variables. In the Galactic plane (b= 0°),N(10.5;l,b) increases in the direction of the Galactic center as |l|−0.30±0.03in the range of − 01 ≥l≥ − 07, but this increase is significantly slower than the increase (|l|−0.44±0.02) of the FexxvKα line intensity. If normalized with the ratios in the outer region 15 ≤ |l| ≤ 28, where faint X-ray point sources are argued to dominate the diffuse Galactic X-ray ridge emission, the excess of the FexxvKα line intensity over the stellar number density is at least a factor of two at |l| = 01. This indicates that a significant part of the Galactic-center diffuse emission arises from a truly diffuse optically thin thermal plasma, and not from an unresolved collection of faint X-ray point sources related to the old stellar population.