Flares from Sgr A* and their Emission Mechanism

K. Dodds-Eden, (1) , D. Porquet, (2) , G. Trap, , E. Quataert, , S. Gillessen, (1) , N. Grosso, (2) , R. Genzel, (1) , A. Goldwurm , F. Yusef-Zadeh, , S. Trippe, , H. Bartko, , F. Eisenhauer, (1) , T. Ott, , T. Fritz, , O. Pfuhl,

1 MPE - Max Planck Institute for Extraterrestrial Physics
2 ObAS - Observatoire astronomique de Strasbourg

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.

Domaines: Planète et Univers [physics]; Astrophysique [astro-ph]; Astrophysique galactique [astro-ph.GA]; Phénomènes cosmiques de haute energie [astro-ph.HE]

K. Dodds-Eden,, D. Porquet,, G. Trap,, E. Quataert,, S. Gillessen,, et al.. Flares from Sgr A* and their Emission Mechanism. The Galactic Center: a Window to the Nuclear Environment of Disk Galaxies, Oct 2009, Shangai, China. ⟨hal-02331038⟩