We summarize recent observations and modeling of the brightest Sgr A* flare to be observed simultaneously in (near)-infrared and X-rays to date. Trying to explain the spectral characteristics of this flare through inverse Compton mechanisms implies physical parameters that are unrealistic for Sgr A*. Instead, a "cooling break" synchrotron model provides a more feasible explanation for the X-ray emission. In a magnetic field of about 5-30 Gauss the X-ray emitting electrons cool very quickly on the typical dynamical timescale while the NIR-emitting electrons cool more slowly. This produces a spectral break in the model between NIR and X-ray wavelengths that can explain the differences in the observed spectral indices.
@article{arxiv.1002.2885,
title = {Flares from Sgr A* and their emission mechanism},
author = {K. Dodds-Eden and D. Porquet and G. Trap and E. Quataert and S. Gillessen and N. Grosso and R. Genzel and A. Goldwurm and F. Yusef-Zadeh and S. Trippe and H. Bartko and F. Eisenhauer and T. Ott and T. K. Fritz and O. Pfuhl},
journal= {arXiv preprint arXiv:1002.2885},
year = {2010}
}
Comments
Proceedings of the Galactic Center Workshop 2009, Shanghai