GRB Light Curves in the Relativistic Turbulence Model

Relativistic Turbulence provides an alternative to internal shocks as a mechanism for producing GRBs’ variable light curves with efficient conversion of energy to radiation. In this model the relativistic outflow is broken into small eddies moving relativistically in the outflow’s rest frame. Variability arises because an observer sees an eddy only when its velocity points towards him and only a small fraction of the eddies are observed. Relativistic turbulence with a significant relativistic velocity requires converting and maintaing a large fraction of the over all energy into turbulent motion. While it is not clear how this is achieved, we explore here, using a toy model, the constraints the model parameters results in light curves comparable to the observations. We find that a tight relation between the size of the eddies and the bulk and turbulent Lorentz factors is needed and that the variability level determines the turbulent Lorentz factor. While the model successfully produces the observed variability there are several inconsistencies with other properties of the light curves. Most of which, but not all, might be resolved if the central engine is active for a long time producing a number of shells, resembling to some extent the internal shocks model.