Understanding the radio beam of PSR J1136+1551 through its single pulses
Understanding the radio beam of PSR J1136+1551 through its single pulses
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DOI：
10.1093/mnras/stz2121
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发表时间：
2019-07
影响因子：
4.8
通讯作者：
L. Oswald;A. Karastergiou;S. Johnston
中科院分区：
文献类型：
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作者：
L. Oswald;A. Karastergiou;S. Johnston
脉冲星轮廓的频率变宽通常归因于在脉冲星表面以上较高的高度产生较低的频率；所谓的半径到频率映射（RFM）观测者看到的脉冲星发射是穿过三维磁层的一维切割：我们只能看到沿着我们视线的发射。然而，通过比较位于不同相位的许多单脉冲的频率演变，我们可以建立对活动发射区域形状的理解。利用巨型米波射电望远镜观测到的单脉冲，研究了PSR J1136+1551的发射区域，并测试了RFM。假设发射产生于磁场线的切向，并且每个发射频率对应于单个高度，我们模拟了由规范锥形光束模型和扇形光束模型产生的单脉冲剖面演变。将模拟结果与观测结果进行比较，得出了用扇形波束模型更好地描述PSR J1136+1551发射区的结论。观测到的单脉冲剖面加宽行为的多样性可以用磁层中沿不同频率相关路径传播的正交极化模式来解释。
The frequency widening of pulsar profiles is commonly attributed to lower frequencies being produced at greater heights above the surface of the pulsar; so-called radius-to-frequency mapping (RFM). The observer’s view of pulsar emission is a 1D cut through a 3D magnetosphere: we can only see that emission which points along our line of sight. However, by comparing the frequency evolution of many single pulses positioned at different phases, we can build up an understanding of the shape of the active emission region. We use single pulses observed with the Giant Metrewave Radio Telescope to investigate the emission region of PSR J1136+1551 and test RFM. Assuming that emission is produced tangential to the magnetic field lines and that each emission frequency corresponds to a single height, we simulate the single pulse profile evolution resulting from the canonical conal beam model and a fan beam model. Comparing the results of these simulations with the observations, we conclude that the emission region of PSR J1136+1551 is better described by the fan beam model. The diversity of profile widening behaviour observed for the single pulses can be explained by orthogonally polarized modes propagating along differing frequency-dependent paths in the magnetosphere.