The Nature of the 10 kilosecond X-ray flare in Sgr A

• Published in: Astronomy and astrophysics (Berlin) 2001-11, Vol.379 (1), p.L13-L16
• Main Authors: Markoff, S., Falcke, H., Yuan, F., Biermann, P. L.
• Format: Article
• Language: English
• Subjects: accretion; accretion disks; black hole physics; galaxies: jets; galaxy: center; radiation mechanisms: non-thermal; X-rays: galaxies
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361:20011346

The X-ray mission Chandra has observed a dramatic X-ray flare -a brightening by a factor of 50 for only three hours -from Sgr A*, the Galactic Center supermassive black hole. Sgr A* has never shown variability of this amplitude in the radio and we therefore argue that a jump of this order in the accretion rate does not seem the likely cause. Based on our model for jet-dominated emission in the quiescent state of Sgr A*, we suggest that the flare is a consequence of extra electron heating near the black hole. This can either lead to direct heating of thermal electrons to $T_{\rm e}\sim6\times 10^{11}$ K and significantly increased synchrotron-self Compton emission, or result from non-thermal particle acceleration with increased synchrotron radiation and electron Lorentz factors up to $\gamma_{\rm e}\ga10^{5}$. While the former scenario is currently favored by the data, simultaneous VLBI, submm, mid-infrared and X-ray observations should ultimately be able to distinguish between the two cases.