The role of stochastic acceleration in the prompt emission of gamma-ray bursts: Application to hadronic injection

We study effects of particle re-acceleration (or heating) in the post-shock region via magnetohydrodynamic/plasma turbulence, in the context of a mixed hadronic-leptonic model for the prompt emission of gamma-ray bursts, using both analytical and numerical methods. We show that stochastically accelerated (or heated) leptons, which are injected via pp and pγ reactions and subsequent pair cascades, are plausibly able to reproduce the Band function spectra with α ∼ 1 and β ∼ 2-3 in the ∼MeV range. An additional hard component coming from the proton-induced cascade emission is simultaneously expected, which can be compatible with observed extra power-law spectra far above the MeV range. We also discuss the specific implications of hadronic models for ongoing high-energy neutrino observations.