STATISTICS OF X-RAY FLARES OF SAGITTARIUS A(star): EVIDENCE FOR SOLAR-LIKE SELF-ORGANIZED CRITICALITY PHENOMENA

X-ray flares have routinely been observed from the supermassive black hole. at our Galactic center, Sagittarius A(star) (Sgr A(star)). The nature of these flares remains largely unclear, despite many theoretical models. In this paper, we study the statistical properties of the Sgr A(star) 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(star) 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 x 10(-3) count s(-1) and a flare component with a power-law fluence distribution dN dE proportional to E-aE with alpha(E)= 1.65. 0.17. The duration-fluence correlation can also be modeled as a power law T proportional to E-alpha ET with alpha(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