Spectropolarimetric Analysis of FRB 181112 at Microsecond Resolution: Implications for Fast Radio Burst Emission Mechanism
Spectropolarimetric Analysis of FRB 181112 at Microsecond Resolution: Implications for Fast Radio Burst Emission Mechanism
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DOI：
10.3847/2041-8213/ab7824
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发表时间：
2020-03-10
影响因子：
7.9
通讯作者：
Tuthill, John
中科院分区：
文献类型：
--
作者：
Cho, Hyerin;Macquart, Jean-Pierre;Tuthill, John
我们开发了一种新的相干去色散模式来研究快速射电暴（FRB）的发射，触发澳大利亚SKA探路者（ASKAP）干涉仪的电压捕获能力。原则上，该模式可以探测发射时间尺度低至3 ns，保留完整的偏振信息。启用的新功能，在这里，我们提出了一个分光偏振分析FRB 181112检测ASKAP，本地化的星系在红移0.47。在微秒的时间分辨率的突发被分解成四个窄脉冲的上升时间仅为15 μ s的最亮。脉冲具有多样性的形态，但没有表现出时间展宽的湍流等离子体沿着视线的证据，也没有任何证据表明其到达时间的周期性。脉冲是高度偏振的（高达95%），偏振位置角在脉冲之间和脉冲内都有变化。脉冲具有变化15的视在旋转测量。2 rad m-2，表观色散测量值变化0.041。0.004 pc cm-3。在最亮的脉冲上观察到线偏振和圆偏振之间的转换。我们的结论是，FRB 181112脉冲是最一致的发射过程的直接表现形式或通过相对论等离子体接近源的传播的结果。这表明，我们的方法，这有利于高时间分辨率的偏振观测FRB，可用于研究不仅突发发射过程，但也存在的传播效应的多样性上的千兆秒差距的路径，他们穿越。
We have developed a new coherent dedispersion mode to study the emission of fast radio bursts (FRBs) that trigger the voltage capture capability of the Australian SKA Pathfinder (ASKAP) interferometer. In principle the mode can probe emission timescales down to 3 ns with full polarimetric information preserved. Enabled by the new capability, here we present a spectropolarimetric analysis of FRB 181112 detected by ASKAP, localized to a galaxy at redshift 0.47. At microsecond time resolution the burst is resolved into four narrow pulses with a rise time of just 15 mu s for the brightest. The pulses have a diversity of morphology, but do not show evidence for temporal broadening by turbulent plasma along the line of sight, nor is there any evidence for periodicity in their arrival times. The pulses are highly polarized (up to 95%), with the polarization position angle varying both between and within pulses. The pulses have apparent rotation measures that vary by 15. 2 rad m-2 and apparent dispersion measures that vary by 0.041. 0.004 pc cm-3. Conversion between linear and circular polarization is observed across the brightest pulse. We conclude that the FRB 181112 pulses are most consistent with being a direct manifestation of the emission process or the result of propagation through a relativistic plasma close to the source. This demonstrates that our method, which facilitates high-time-resolution polarimetric observations of FRBs, can be used to study not only burst emission processes, but also a diversity of propagation effects present on the gigaparsec paths they traverse.