Cosmic-Ray Production and X-Ray and Gamma-Ray Emission from the Galactic Center

Abstract

We assume that the energy source in the Galactic Center is the black hole Sgr A * , which becomes active when a star is captured in a rate of ∼10 -5 yr -1 . During the active phase relativistic protons with a characteristic energy ∼6 ×10 52 erg per capture are ejected. We suppose that the annihilation of secondary positrons produced by proton-proton collisions is observed as the 511 keV line flux from the Galactic bulge. Though these positron are generated with relatively high energies (>30 MeV), our model satisfy the criterion derived by Beacom and Yuksel based on the COMPTEL data in the range 1–30 MeV. From our estimations it follows also that a flux of gamma-ray de-excitation lines ∼2.5 ×10 -5 ph cm -2 s -1 in the range below 8 MeV is produced by the relativistic protons in the Galactic center. A specific line is the one at 1.809 MeV from radioactivity of 26 Al. The predicted quasi-stationary flux of the 26 Al 1.809 MeV line from the 1° ×1° central region is ≤10 -6 ph cm -2 s -1 . We conclude also the ...