  Based on the collective linear and nonlinear processes in a magnetized plasma
surrounding the black hole at the galactic center (GC), an acceleration
mechanism is proposed to explain the recent detection/discovery of PeV protons.
In a two stage process, the gravitation energy is first converted to the
electrical energy in fast growing Langmuir waves, and then the electrical
energy is transformed to the particle kinetic energy through Landau damping of
waves. It is shown that, for the characteristics parameters of GC plasma,
proton energy can be boosted upto 5PeV.
