1998ApJ...509L..81T

Some recent experiments detecting very high energy (VHE) gamma rays above 10-20 TeV independently reported VHE bursts for some bright gamma-ray bursts (GRBs). If these signals are truly from GRBs, these GRBs must emit a much larger amount of energy as VHE gamma rays than in the ordinary photon energy range of GRBs (keV-MeV). We show that such extreme phenomena can be reasonably explained by synchrotron radiation of protons accelerated to ∼10²⁰-10²¹ eV, which we predicted recently. Protons seem to carry about (m_p_/m_e) times larger energy than electrons, and hence the total energy liberated by one GRB becomes as large as ∼10⁵⁶ (ΔΩ/4π) ergs. Therefore, a strong beaming of GRB energy is highly likely. Extension of the VHE spectrum beyond 20 TeV gives a nearly model-independent lower limit of the Lorentz factor of GRBs, as γ≳500. Furthermore, our model gives the correct energy range and time variability of ordinary keV-MeV gamma rays of GRBs by synchrotron radiation of electrons. Therefore, the VHE bursts of GRBs strongly support the hypothesis that ultra-high-energy cosmic rays observed on the Earth are produced by GRBs.