Abstract
X-ray flares have routinely been observed from the supermassive black hole at our Galactic center, Sagittarius A{}\star (Sgr A⋆). The nature of these flares remains largely unclear, despite many theoretical models. In this paper, we study the statistical properties of the Sgr A⋆ 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⋆ 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}-3 count s-1 and a flare component with a power-law fluence distribution {dN}/{dE}\propto {E}-{α {{E}}} with {α }{{E}}=1.65+/- 0.17. The duration-fluence correlation can also be modeled as a power law T\propto {E}{α {ET}} with {α }{ET}\lt 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.
Author
Li, Ya-Ping; Yuan, Feng; Yuan, Qiang; Wang, Q. Daniel; Chen, P. F.; Neilsen, Joseph; Fang, Taotao; Zhang, Shuo; Dexter, Jason
Journal
Astrophysical Journal
Paper Publication Date
September 2015
Paper Type
Astrostatistics