Shallow Decay of Early X-Ray Afterglows from Inhomogeneous Gamma-Ray Burst Jets
Shallow Decay of Early X-Ray Afterglows from Inhomogeneous Gamma-Ray Burst Jets
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DOI：
10.1086/503384
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发表时间：
2005-11
期刊：
影响因子：
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通讯作者：
K. Toma;K. Ioka;R. Yamazaki;Takashi Nakamura
中科院分区：
文献类型：
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作者：
K. Toma;K. Ioka;R. Yamazaki;Takashi Nakamura
几乎所有由雨燕卫星观测到的γ射线暴（GRB）的X射线余辉在最初的几千秒内都有一个浅衰变阶段。我们表明，在一个不相干的喷流模型（多subjet或补丁壳），离轴subjet（补丁壳）的余辉的叠加可以产生浅衰减相。获得浅衰变相的必要条件是，γ射线明亮的次射流（斑片壳层）具有比先前估计的更高的γ射线效率，并且它们被γ射线效率低的γ射线暗淡的次射流（斑片壳层）包围。我们的模型预测，事件与暗淡的即时发射将有一个传统的余辉光曲线没有一个浅衰变阶段，如GRB 050416 A。
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.