Statistics of X-Ray Flares of Sagittarius A*: Evidence for Solar-like Self-organized Criticality Phenomena
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.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 2015
- DOI:
- 10.1088/0004-637X/810/1/19
- arXiv:
- arXiv:1506.02946
- Bibcode:
- 2015ApJ...810...19L
- Keywords:
-
- accretion;
- accretion disks;
- black hole physics;
- Galaxy: center;
- methods: statistical;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Instrumentation and Methods for Astrophysics
- E-Print:
- to appear in ApJ