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

The X-ray mission Chandra has observed a dramatic X-ray are - 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 are is a consequence of extra electron heating near the black hole. This can either lead to direct heating of thermal electrons to T-e similar to 6 x 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 (e) greater than or similar to 10(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.