GeV Emission from Collisional Magnetized Gamma Ray Bursts
  Magnetic fields may play a dominant role in gamma-ray bursts, and recent observations by the Fermi satellite indicate that GeV radiation, when detected, arrives delayed by seconds from the onset of the MeV component. Motivated by this, we discuss a magnetically dominated jet model where both magnetic dissipation and nuclear collisions are important. We show that, for parameters typical of the observed bursts, such a model involving a realistic jet structure can reproduce the general features of the MeV and a separate GeV radiation component, including the time delay between the two. The model also predicts a multi-GeV neutrino component. 
P. M\'esz\'aros, M.J. Rees
astro-ph.HE hep-ph