Ten per cent polarized optical emission from GRB 090102
Ten per cent polarized optical emission from GRB 090102
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DOI：
10.1038/nature08590
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发表时间：
2009-12
期刊：
影响因子：
64.8
通讯作者：
I. Steele;C. Mundell;R. Smith;S. Kobayashi;C. G. Ari;Liverpool John Moore's University;U. Ferrara-U.-Ferrar
中科院分区：
文献类型：
--
作者：
I. Steele;C. Mundell;R. Smith;S. Kobayashi;C. G. Ari;Liverpool John Moore's University;U. Ferrara-U.-Ferrar
喷流的性质和磁场在伽马射线暴（GRBs）中的作用仍不清楚。在重子主导的射流中，只有在激波的情况下产生的微弱的纠结场才会存在。在另一种模型中，喷流被源自中央发动机的大规模磁场所缠绕，这些磁场加速并校准了物质。为了区分两种模式，必须测量早期发射的极化程度；然而，之前关于伽马射线极化的说法一直存在争议。在这里，我们报告了GRB 090102的早期光学发射在10±1%的偏振，表明存在起源于膨胀火球的大规模场。如果偏振度和它的位置角度在短于我们60秒曝光的时间尺度上是可变的，那么峰值偏振可能大于10%。
The nature of the jets and the role of magnetic fields in gamma-ray bursts (GRBs) remains unclear,. In a baryon-dominated jet only weak, tangled fields generatedin situthrough shocks would be present. In an alternative model, jets are threaded with large-scale magnetic fields that originate at the central engine and that accelerate and collimate the material. To distinguish between the models the degree of polarization in early-time emission must be measured; however, previous claims of gamma-ray polarization have been controversial,,,. Here we report that the early optical emission from GRB 090102 was polarized at 10 ± 1 per cent, indicating the presence of large-scale fields originating in the expanding fireball. If the degree of polarization and its position angle were variable on timescales shorter than our 60-second exposure, then the peak polarization may have been larger than ten per cent.