Restrictions on the injection energy of positrons annihilating near the
  Galactic center
  The origin and properties of the source of positrons annihilating in the
Galactic Center is still a mystery. One of the criterion, which may
discriminate between different mechanisms of positron production there, is the
positron energy injection. Beacom and Yueksel (2006) suggested a method to
estimate this energy from the ratio of the 511 keV line to the MeV in-flight
annihilation fluxes. From the COMPTEL data they derived that the maximum
injection energy of positron should be about several MeV that cut down
significantly a class of models of positron origin in the GC assuming that
positrons lose their energy by Coulomb collisions only. However, observations
show that the strength of magnetic field in the GC is much higher than in other
parts of the Galaxy, and it may range there from 100 $\mu$G to several mG. In
these conditions, synchrotron losses of positrons are significant that extends
the range of acceptable values of positron injection energy. We show that if
positrons injection in the GC is non-stationary and magnetic field is higher
than 0.4 mG both radio and gamma-ray restrictions permit their energy to be
higher than several GeV.
