SHOCK CORRUGATION BY RAYLEIGH–TAYLOR INSTABILITY IN GAMMA-RAY BURST AFTERGLOW JETS
SHOCK CORRUGATION BY RAYLEIGH–TAYLOR INSTABILITY IN GAMMA-RAY BURST AFTERGLOW JETS
复制标题
伽马射线爆裂余辉射流中瑞利-泰勒不稳定性引起的冲击波纹
DOI：
10.1088/2041-8205/791/1/l1
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
A. MacFadyen
中科院分区：
文献类型：
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作者：
P. Duffell;A. MacFadyen
余辉射流是瑞利-泰勒不稳定的，因此在减速的早期阶段是湍流。还有一些主动冷却射流的过程。在这封信中，我们证明，如果冷却显着增加了流动的可压缩性，则湍流会与前向激波发生碰撞，从而使其不稳定并产生波纹。在这种情况下，前向激波的湍流足以通过小型湍流发电机产生负责同步加速器发射的磁场。我们假设磁场与湍流动能能量均分来计算光变曲线，并发现动态磁场可以很好地近似为 1% 的恒定磁热能比，尽管峰值通量的时间存在相当大的延迟，因为磁场仅在湍流激活后才开启。研究发现，反向激波的磁化程度明显高于正向激波，磁能与热能之比约为 10%。这项工作激发了未来使用更多物理冷却模型的瑞利-泰勒计算。
Afterglow jets are Rayleigh–Taylor unstable and therefore turbulent during the early part of their deceleration. There are also several processes which actively cool the jet. In this Letter, we demonstrate that if cooling significantly increases the compressibility of the flow, the turbulence collides with the forward shock, destabilizing and corrugating it. In this case, the forward shock is turbulent enough to produce the magnetic fields responsible for synchrotron emission via small-scale turbulent dynamo. We calculate light curves assuming the magnetic field is in energy equipartition with the turbulent kinetic energy and discover that dynamic magnetic fields are well approximated by a constant magnetic-to-thermal energy ratio of 1%, though there is a sizeable delay in the time of peak flux as the magnetic field turns on only after the turbulence has activated. The reverse shock is found to be significantly more magnetized than the forward shock, with a magnetic-to-thermal energy ratio of the order of 10%. This work motivates future Rayleigh–Taylor calculations using more physical cooling models.