Statistics of X-ray flares of Sagittarius A{sup ⋆}: Evidence for solar-like self-organized criticality phenomena
- Department of Astronomy and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen, Fujian 361005 (China)
- Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States)
- School of Astronomy and Space Science, Nanjing University, Nanjing 210023 (China)
- Boston University Department of Astronomy, Boston, MA 02215 (United States)
- Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States)
- Max Planck Institute for Extraterrestrial Physics, P.O. Box 1312, Giessenbachstr., D-85741 Garching (Germany)
X-ray flares have routinely been observed from the supermassive black hole at our Galactic center, Sagittarius A{sup ⋆} (Sgr A{sup ⋆}). The nature of these flares remains largely unclear, despite many theoretical models. In this paper, we study the statistical properties of the Sgr A{sup ⋆} X-ray flares by fitting the count rate (CR) distribution and the structure function of the light curve with a Markov Chain Monte Carlo method. With the 3-million-second Chandra observations accumulated in the Sgr A{sup ⋆} X-ray Visionary Project, we construct the theoretical light curves through Monte Carlo simulations. We find that the 2–8 keV X-ray light curve can be decomposed into a quiescent component with a constant CR of 6×10{sup −3} count s{sup −1} and a flare component with a power-law fluence distribution dN/dE∝E{sup −α{sub E}} with α{sub E}=1.65±0.17. The duration–fluence correlation can also be modeled as a power law T∝E{sup α{sub E}{sub T}} with α{sub ET}<0.55 (95% confidence). These statistical properties are consistent with the theoretical prediction of the self-organized criticality system with the spatial dimension S = 3. We suggest that the X-ray flares represent plasmoid ejections driven by magnetic reconnection (similar to solar flares) in the accretion flow onto the black hole.
- OSTI ID:
- 22882732
- Journal Information:
- Astrophysical Journal, Vol. 810, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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