2009ApJ...705.1714A

We propose a new mechanism for the prompt emission of gamma-ray burst. In our model, electrons are continuously accelerated in the post-shock region via plasma turbulence. Using the Monte Carlo technique, we mimic the second-order Fermi acceleration due to plasma turbulence and obtain photon spectra. Since the acceleration balances with the synchrotron cooling, the observed low-energy spectral index is naturally explained. The resultant spectra can be consistent with observed spectra at least below ∼1 MeV. The model also predicts delayed GeV-TeV emission due to inverse Compton and broad pulse profile of optical emission in some cases. Although nontrivial assumptions are required to reproduce MeV-GeV power-law spectra, the model implies the possibility of explaining various kinds of luminosity correlations.