Shallow Decay of Early X-Ray Afterglows from Inhomogeneous Gamma-Ray Burst Jets

Kenji Toma, Kunihito Ioka, Ryo Yamazaki, Takashi Nakamura
2006 Astrophysical Journal  
Almost all the X-ray afterglows of gamma-ray bursts (GRBs) observed by the Swift satellite have a shallow decay phase in the first thousands of seconds. We show that in an inhomogeneous jet (multiple-subjet or patchy-shell) model the superposition of the afterglows of off-axis subjets (patchy shells) can have the shallow decay phase. The necessary condition for obtaining the shallow decay phase is that gamma-ray bright subjets (patchy shells) should have gamma-ray efficiency higher than
more » ... ly estimated, and should be surrounded by gamma-ray dim subjets (patchy shells) with low gamma-ray efficiency. Our model predicts that events with dim prompt emission have the conventional afterglow light curve without the shallow decay phase like GRB 050416A.
doi:10.1086/503384 fatcat:ktqm4gzqezaezme46rcfci5px4