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Paper: Gamma-Rays from the Galactic Center: A Point-Like or Diffuse Source?
Volume: 186, The Central Parsecs of the Galaxy
Page: 551
Authors: Markoff, S.; Melia, F.
Abstract: EGRET has detected a γ-ray flux from the Galactic center region, but its resolution is not sufficient to determine the exact source. While the lack of variation in the flux down to detector sensitivity suggests a diffuse emitter, a compact source (possibly coincident with the massive black hole candidate Sgr A*) cannot be ruled out on this basis: recent hydrodynamical simulations of the accretion process indicate that a lower level of fluctuation is consistent with this amplitude on a time-scale comparable to the current observation timeline. Until instruments with the capability to resolve the details of this region at extremely high-energies are available, we are left to determine the source by identifying the most likely candidates and attempting to model their spectra based on what we know of their physical environments. We present some details of the general model here, and its particular application to Sgr A*. A detailed analysis of the photon production from hadronic collisions and other processes, using the most current particle physics data and theoretical models, indicates that an accreting black hole environment is inconsistent with the broad-band data.
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