High energy radiation from the direction of the galactic black hole Sgr A |
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Authors: | KS Cheng DO Chernyshov V Dogiel |
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Institution: | 1. Department of Physics, The University of Hong Kong, Hong Kong, China;2. Moscow Institute of Physics and Technology, Institutskii lane, 141700 Moscow Region, Dolgoprudnii, Russia;3. I.E.Tamm Theoretical Physics Division of P.N.Lebedev Institute, Leninskii pr, 53, 119991 Moscow, Russia |
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Abstract: | X-ray observations indicate that the Galactic black hole Sgr A∗ is inactive now, however, we suggest that Sgr A∗ can become active when a captured star is tidally disrupted and matter is accreted into the black hole. Consequently the Galactic black hole could be a powerful source of relativistic protons with a characteristic energy ∼1052 erg per capture. The diffuse GeV and TeV γ-rays emitted in the direction of the Galactic Center (GC) are the direct consequences of p–p collisions of such relativistic protons ejected by very recent capture events occurred ?105 yr ago. On the other hand, the extended electron-positron annihilation line emission observed from GC is a phenomenon related to a large population of thermalized positrons, which are produced, cooled down and accumulated through hundreds of past capture events during a period of ∼107 yr. In addition to explaining GeV, TeV and 511 keV annihilation emissions we also estimate the photon flux of several MeV resulting from in-flight annihilation process. |
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Keywords: | Galactic black hole γ-rays Radiation processes |
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