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

Toma Kenji

Ioka Kunihito

Yamazaki Ryo

Nakamura Takashi

The Astrophysical Journal

Almost all the X-ray afterglows of γ-ray bursts (GRBs) observed by the Swift satellite have a shallow decay phase in their first few thousand seconds. We show that in an inhomogeneous-jet model (multiple-subjet or patchy-shell), the superposition of the afterglows of off-axis subjets (patchy shells) can produce the shallow decay phase. The necessary condition for obtaining the shallow decay phase is that γ-ray–bright subjets (patchy shells) have γ-ray efficiencies higher than previously estimated and that they be surrounded by γ-ray–dim subjets (patchy shells) with low γ-ray efficiency. Our model predicts that events with dim prompt emission will have a conventional afterglow light curve without a shallow decay phase, like GRB 050416A.

天文学・宇宙科学 [ 440 ]

英語

The American Astronomical Society

Copyright (c) 2006. The American Astronomical Society

[ISSN] 0004-637X

[DOI] 10.1086/503384

[DOI] http://dx.doi.org/10.1086/503384 ～の異版である