Publications
of the
MPIfR
Optical & Infrared
Interferometry Group
S. Markoff, H. Falcke, F. Yuan, and
P.L. Biermann:
The nature of the 10 kilosecond X-ray flare
in Sgr A*
Astronomy and Astrophysics 379, L13-L16 (2001)
Abstract.
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_e~6*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>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.
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