We motivate how the most recent progress in the understanding the nature of the GeV radiation in most energetic gamma-ray bursts ( GRBs ) , the binary-driven hypernovae ( BdHNe ) , has led to the solution of a forty years unsolved problem in relativistic astrophysics : how to extract the rotational energy from a Kerr black hole for powering synchrotron emission and ultra high-energy cosmic rays .
The inner engine is identified in the proper use of a classical solution introduced by Wald in 1974 duly extended to the most extreme conditions found around the newborn black hole in a BdHN .
The energy extraction process occurs in a sequence impulsive processes each accelerating protons to 10 ^ { 21 } eV in a timescale of 10 ^ { -6 } s and in presence of an external magnetic field of 10 ^ { 14 } G. Specific example is given for a black hole of initial angular momentum J = 0.3 M ^ { 2 } and mass M \approx 3 M _ { \odot } leading to the GeV radiation of 10 ^ { 49 } erg \cdot s ^ { -1 } .
The process can energetically continue for thousands of years .