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Beacom and Yüksel (2006) suggested an elegant method to esti mate an initial energy of annihilating positrons from the ratio of 511 keV line and in-flight a nnihilation fluxes. The idea was that in the case of stationary injection of positrons at high ener gies the fluxes of 511 keV line emission (generated by thermalized positrons) and of in-flight annih ilation (produced by fast positrons) were proportional to each other. For the delta-function inj ection spectrum they showed that the initial energy of annihilating positrons cannot exceed 3 Me V. Otherwise the expected in-flight annihilation flux of fast positrons in the range 1 to 10 MeV is hig er than observed by COMPTEL. However, the conclusion may be changed significantly if one a nalyzes the spatial distribution of the 511 keV emission and 1-10 MeV emission. In addition if the magnetic field in Galactic center region is 1 mG or higher the injection energy of positrons pro duced by central compact source can be unrestricted.

Restrictions on the injection energy of positrons annihilating near the Galactic center