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Optical Flash of GRB 990123: constraints on the physical parameter of the reverse shock

Y. Z. Fan·Z. G. Dai·Y. F. Huang·T. Lu
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Abstract

The optical flash accompanying GRB 990123 is believed to be powered by the reverse shock of a thin shell. With the best fitted physical parameters for GRB 990123 (Panaitescu & Kumar 2001) and the assumption that the parameters in the optical flash are the same as those in the afterglow, we show that: 1) the shell is thick but not thin, and we have provided the light curve for the thick shell case which coincides with the observation; 2) the theoretical peak flux of the optical flash accounts for only 3\times10^{-4} of the observed. In order to compensate this divergency, the physical parameters the electron energy ration and the magnetic ratio $ε_e$, $ε_B$ should be 0.61, 0.39 respectively, which are much different from those in the late afterglow.

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Y. Z. Fan, Z. G. Dai, Y. F. Huang, T. Lu. 2003-06-02. Optical Flash of GRB 990123: constraints on the physical parameter of the reverse shock. https://doi.org/10.1088/1009-9271%2F2%2F5%2F449

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