Time-varying Polarized Gamma-Rays from GRB 160821A: Evidence for Ordered Magnetic Fields
Time-varying Polarized Gamma-Rays from GRB 160821A: Evidence for Ordered Magnetic Fields
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DOI：
10.3847/2041-8213/ab3a48
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发表时间：
2019-08
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通讯作者：
V. Sharma;S. Iyyani;D. Bhattacharya;T. Chattopadhyay;A. R. Rao;E. Aarthy;S. Vadawale;N. Mithun;V. Bhalerao;F. Ryde;A. Peer
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作者：
V. Sharma;S. Iyyani;D. Bhattacharya;T. Chattopadhyay;A. R. Rao;E. Aarthy;S. Vadawale;N. Mithun;V. Bhalerao;F. Ryde;A. Peer
GRB 160821 A是费米伽马射线太空望远镜观测到的第三大伽马射线暴。根据AstroSat上的碲锌镉成像仪的观测结果，我们报告了迄今为止最确凿的证据：（i）高线性偏振（检测），和（ii）偏振角随时间的变化，分别在3.5σ和3.1σ检测的爆发的上升和衰减阶段发生两次。报告了两个感兴趣参数的所有置信水平。这些观测结果强烈表明，同步辐射产生于磁场线中，这些磁场线在1/Γ的角度尺度上是高度有序的，其中Γ是外流的洛伦兹因子。
GRB 160821A is the third most energetic gamma-ray burst observed by the Fermi gamma-ray space telescope. Based on the observations made by the Cadmium Zinc Telluride Imager on board AstroSat, here we report the most conclusive evidence to date of (i) high linear polarization ( detection), and (ii) variation of polarization angle with time, occurring twice during the rise and decay phase of the burst at 3.5σ and 3.1σ detections, respectively. All confidence levels are reported for two parameters of interest. These observations strongly suggest synchrotron radiation produced in magnetic field lines that are highly ordered on angular scales of 1/Γ, where Γ is the Lorentz factor of the outflow.