Variation of microphysics in wind bubbles: an alternative mechanism for explaining the rebrightenings in GRB afterglows

摘要

Conventionally, long GRBs are thought to be caused by the core collapses ofmassive stars. During the lifetime of a massive star, a stellar wind bubbleenvironment should be produced. Furthermore, the microphysics shock parametersmay vary along with the evolution of the fireball. Here we investigate thevariation of the microphysics shock parameters under the condition of windbubble environment, and allow the microphysics shock parameters to bediscontinuous at shocks in the ambient medium. It is found that our model canacceptably reproduce the rebrightenings observed in GRB afterglows, at least insome cases. The effects of various model parameters on rebrightenings areinvestigated. The rebrightenings observed in both the R-band and X-rayafterglow light curves of GRB 060206, GRB 070311 and GRB 071010A are reproducedin this model.