High energy radiation from the direction of the galactic black hole Sgr A^*

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• 作者：K.S. Cheng ; D.O. Chernyshov ; V. Dogiel
• 关键词：Galactic black hole ; γ ; -rays ; Radiation processes
• 刊名：Advances in Space Research
• 出版年：2008
• 出版时间：5 August 2008
• 年：2008
• 卷：42
• 期：3
• 页码：538-543
• 全文大小：198 K

文摘

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 alt=""not, vert, similar"" title=""not, vert, similar"" border=""0"">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 a7d.gif"" alt=""less-than-or-equals, slant"" title=""less-than-or-equals, slant"" border=""0"">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 alt=""not, vert, similar"" title=""not, vert, similar"" border=""0"">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.