Shallow decay of early X-ray afterglows from inhomogeneous gamma-ray burst jets

Kenji Toma, Kunihito Ioka, Ryo Yamazaki, Takashi Nakamura

Research output: Contribution to journalArticlepeer-review

40 Citations (Scopus)


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 patchyshell), 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.

Original languageEnglish
Pages (from-to)L139-L142
JournalAstrophysical Journal
Issue number2 II
Publication statusPublished - 2006 Apr 1


  • Gamma rays: bursts
  • Gamma rays: theory


Dive into the research topics of 'Shallow decay of early X-ray afterglows from inhomogeneous gamma-ray burst jets'. Together they form a unique fingerprint.

Cite this