Early Optical Polarization of a Gamma-Ray Burst Afterglow
Early Optical Polarization of a Gamma-Ray Burst Afterglow
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DOI：
10.1126/science.1138484
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发表时间：
2007-03
期刊：
影响因子：
56.9
通讯作者：
C. Mundell;I. Steele;Robert J. Smith;S. Kobayashi;A. Melandri;C. Guidorzi;A. Gomboc;C. Mottram;D. Clarke;A. Monfardini;D. Carter;D. Bersier
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文献类型：
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作者：
C. Mundell;I. Steele;Robert J. Smith;S. Kobayashi;A. Melandri;C. Guidorzi;A. Gomboc;C. Mottram;D. Clarke;A. Monfardini;D. Carter;D. Bersier
我们报道了伽玛射线暴（GRB）余辉的光学偏振，获得了203秒后，从GRB 060418的初始爆发的γ射线，使用机器人利物浦望远镜的环形偏振计。我们对极化百分比的鲁棒（2σ）上限，小于8%，与余辉开始时的火球减速时间一致。在这个关键时刻的光学亮度和低偏振的衰减率的组合约束标准模型的伽玛暴喷出物，排除了一个大规模的有序的磁场在发射区域的存在。
We report the optical polarization of a gamma-ray burst (GRB) afterglow, obtained 203 seconds after the initial burst of γ-rays from GRB 060418, using a ring polarimeter on the robotic Liverpool Telescope. Our robust (2σ) upper limit on the percentage of polarization, less than 8%, coincides with the fireball deceleration time at the onset of the afterglow. The combination of the rate of decay of the optical brightness and the low polarization at this critical time constrains standard models of GRB ejecta, ruling out the presence of a large-scale ordered magnetic field in the emitting region.