Comptonization model for Prompt optical and infrared emission of GRB 041219A

摘要

Prompt optical emission from the $\gamma$-ray burst of GRB 041219A has been reported by \citet{ves05}. The facts that the fast rise of optical emission simultaneous with the dominant $\gamma$-ray pulse, and a tight correlation with the prompt $\gamma$-ray emission have been displayed. These indicate that the prompt optical emission and $\gamma$-ray emission would naturally have a common origin. We then propose that this optical component could be modelled by considering the $Comptonization$ of $\gamma$-ray photons by an electron cloud. As a result of this mechanism, the arrival time of the optical photons is delayed comparing with that of the $\gamma$-rays. We restrict that the lagging time is shorter than 10 s, within which the prompt optical emission is considered as varying simultaneously with the prompt $\gamma$-ray emission. Taking into account of the observations of GRB 041219A, we derive the number density of the surrounding electron cloud required by $Comptonization$. The red-shift of GRB 041219A is predicted as $z\lesssim 0.073$ as well.