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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
2018
Source PublicationMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
ISSN0035-8711
Volume473Issue:1Pages:306-316
Abstract

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.

Keywordaccretion, accretion discs methods: data analysis Galaxy: centre X-rays: individual (Sgr A*)
DOI10.1093/mnras/stx2408
WOS KeywordSELF-ORGANIZED CRITICALITY ; SUPERMASSIVE BLACK-HOLE ; SAGITTARIUS-A ; XMM-NEWTON ; GAMMA-RAY ; MAGNETOHYDRODYNAMIC MODEL ; GALACTIC-CENTER ; SOLAR-FLARES ; ACCRETION ; EMISSION
Indexed BySCI
Language英语
WOS Research AreaAstronomy & Astrophysics
WOS SubjectAstronomy & Astrophysics
WOS IDWOS:000415653600025
PublisherOXFORD UNIV PRESS
Citation statistics
Cited Times:4[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Identifierhttp://libir.pmo.ac.cn/handle/332002/18218
Collection中国科学院紫金山天文台
Corresponding AuthorYuan, Qiang; Wang, Q. Daniel
Affiliation1.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
Recommended Citation
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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