Diffusion spectra of ultrarelativistic unevenly moving shell radiation

Abstract

We consider the dependence of diffusion spectra on acceleration and deceleration of the shell, which can be caused by the interaction of the shell with the environment, on the duration of the action of the gamma-ray burst (GRB) source and on the period of its action. With periodic action of the GRB source, a second maximum appears in the diffusion spectra at high frequencies. The closest to typical value of the low-energy spectral index is obtained for a decelerating shell with a duration of action of the GRB source not less than the diffusion time; the values of the high-energy spectral indices for the decelerating shell correspond to typical ones.