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A systematic Chandra study of Sgr A*: II. X-ray flare statistics
Yuan, Qiang1,2; Wang, Q. Daniel3; Liu, Siming1,2; Wu, Kinwah4
刊名MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
2018
卷号473期号:1页码:306-316
关键词accretion, accretion discs methods: data analysis Galaxy: centre X-rays: individual (Sgr A*)
ISSN号0035-8711
DOI10.1093/mnras/stx2408
英文摘要

The routinely flaring events from Sgr A* trace dynamic, high-energy processes in the immediate vicinity of the supermassive black hole. We statistically study temporal and spectral properties, as well as fluence and duration distributions, of the flares detected by the Chandra X-ray Observatory from 1999 to 2012. The detection incompleteness and bias are carefully accounted for in determining these distributions. We find that the fluence distribution can be well characterized by a power law with a slope of 1.73(-0.19)(+ 0.20), while the durations (tau in seconds) by a lognormal function with a mean log(tau) = 3.39(-0.24)(+0.27) and an intrinsic dispersion sigma = 0.28(-0.06)(+0.08). No significant correlation between the fluence and duration is detected. The apparent positive correlation, as reported previously, is mainly due to the detection bias (i.e. weak flares can be detected only when their durations are short). These results indicate that the simple self-organized criticality model has difficulties in explaining these flares. We further find that bright flares usually have asymmetric light curves with no statistically evident difference/preference between the rising and decaying phases in terms of their spectral/timing properties. Our spectral analysis shows that although a power-law model with a photon index of 2.0 +/- 0.4 gives a satisfactory fit to the joint spectra of strong and weak flares, there is weak evidence for a softer spectrum of weaker flares. This work demonstrates the potential to use statistical properties of X-ray flares to probe their trigger and emission mechanisms, as well as the radiation propagation around the black hole.

WOS关键词SELF-ORGANIZED CRITICALITY ; SUPERMASSIVE BLACK-HOLE ; SAGITTARIUS-A ; XMM-NEWTON ; GAMMA-RAY ; MAGNETOHYDRODYNAMIC MODEL ; GALACTIC-CENTER ; SOLAR-FLARES ; ACCRETION ; EMISSION
WOS研究方向Astronomy & Astrophysics
语种英语
出版者OXFORD UNIV PRESS
WOS记录号WOS:000415653600025
内容类型期刊论文
源URL[http://libir.pmo.ac.cn/handle/332002/18217]  
专题中国科学院紫金山天文台
通讯作者Yuan, Qiang; Wang, Q. Daniel
作者单位1.Chinese Acad Sci, Purple Mt Observ, Key Lab Dark Matter & Space Astron, Nanjing 210008, Jiangsu, Peoples R China
2.Univ Sci & Technol China, Sch Astron & Space Sci, Hefei 230026, Anhui, Peoples R China
3.Univ Massachusetts, Dept Astron, 710 North Pleasant St, Amherst, MA 01003 USA
4.Univ Coll London, Mullard Space Sci Lab, Dorking RH5 6NT, Surrey, England
推荐引用方式
GB/T 7714
Yuan, Qiang,Wang, Q. Daniel,Liu, Siming,et al. A systematic Chandra study of Sgr A*: II. X-ray flare statistics[J]. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,2018,473(1):306-316.
APA Yuan, Qiang,Wang, Q. Daniel,Liu, Siming,&Wu, Kinwah.(2018).A systematic Chandra study of Sgr A*: II. X-ray flare statistics.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,473(1),306-316.
MLA Yuan, Qiang,et al."A systematic Chandra study of Sgr A*: II. X-ray flare statistics".MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 473.1(2018):306-316.
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