A statistical analysis of point-like sources in the Chandra Galactic Center Survey

被引:3
作者
Wu, J. F.
Zhang, S. N.
Lu, F. J.
Jin, Y. K.
机构
[1] Tsing Hua Univ, Dept Phys, Beijing 100084, Peoples R China
[2] Tsing Hua Univ, Ctr Astrophys, Beijing 100084, Peoples R China
[3] Chinese Acad Sci, Inst High Energy Phys, Key Lab Particle Astrophys, Beijing 100049, Peoples R China
[4] Tsing Hua Univ, Dept Engn Phys, Beijing 100084, Peoples R China
来源
CHINESE JOURNAL OF ASTRONOMY AND ASTROPHYSICS | 2007年 / 7卷 / 01期
关键词
methods : data analysis; Galaxy : center; X-ray : stars;
D O I
10.1088/1009-9271/7/1/05
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
The Chandra Galactic Center Survey detected similar to 800 X-ray point-like sources in the 2 degrees x 0.8 degrees sky region around the Galactic Center. We study the spatial and luminosity distributions of these sources according to their spectral properties. Fourteen bright sources detected are used to fit jointly an absorbed power-law model, from which the power-law photon index is determined to be similar to 2.5. Assuming that all other sources have the same power-law form, the relation between hardness ratio and HI column density N-H is used to estimate the NH values for all sources. Monte Carlo simulations show that these sources are more likely concentrated in the Galactic center region, rather than distributed throughout the Galactic disk. We also find that the luminosities of the sources are positively correlated with their HI column densities, i.e., a more luminous source has a higher HI column density. From this relation, we suggest that the X-ray luminosity comes from the interaction between an isolated old neutron star and interstellar medium (mainly dense molecular clouds). Using the standard Bondi accretion theory and the statistical information of molecular clouds in the Galactic center, we confirm this positive correlation and calculate the luminosity range in this scenario, which is consistent with the observation (10(32)-10(35) erg s(-1)).
引用
收藏
页码:81 / 90
页数:10
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