IS THE AFTERGLOW OF GAMMA-RAY BURST GRB 021004 UNUSUAL?

摘要

The afterglow (AG) of gamma-ray burst GRB 021004 has been claimed to be unusual. In the cannonball (CB) model of GRBs, that is not the case. The very early AG's shape is, like for GRB 990123, a direct tracer of the expected circumburst density profile. The unprecedented precision of the data allows for the "resolution" of two CBs in the AG. These two CBs correspond to the two pulses in the GRB and to the two wide shoulders in the AG light curve. The smaller wiggles in the AG are, like for GRB 000301c and for GRB 970508, to be expected: they trace moderate deviations from a constant density interstellar medium. The observed evolution of the optical spectrum is that predicted in the CB model. The X-ray and radio emissions of GRB 021004 are also normal.