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S. Markoff (MIT, Center for Space Research), H. Falcke (Max-Planck-Institut fuer Radioastronomie, Bonn)
During its second Galactic center observing cycle, the X-ray mission Chandra detected a major flaring event from the central supermassive black hole Sgr A*. During this flare, the flux increased by a factor of ~50, while the smallest timescale of ~600 s argued for an origin within ~40 rg of the central engine. This size scale places the source of the flaring in the inner regions of either the accretion flow or jet outflows. At the time we showed how an additional electron heating process near the base of the jet could account for both the flux and duration of the flared emission. Depending on whether the underlying physical heating mechanism resulted in a quasi-thermal or non-thermal electron distribution, we predicted significantly different simultaneous multi-wavelength behavior. Now in an unprecedented multi-wavelength campaign, Chandra has once again detected flares in Sgr A*, this time with smaller amplitudes and rather stringent limits on the lower-frequency simultaneous emission. We discuss how the predictions of our preliminary models fare against the new flare data, and whether the physical mechanisms at work can be constrained by the multi-wavelength data set. (S.M. is supported by an NSF Astronomy & Astrophysics Postdoctoral Fellowship).
Bulletin of the American Astronomical Society,
© 2003. The American Astronomical Soceity.