用MeerKAT发现灯塔星云中的无线电条纹——粒子从尾部逃逸并照亮周围磁场
Radio streaks in the Lighthouse Nebula discovered with MeerKAT -- Particles escaping from the tail and illuminating the ambient magnetic field
AI总结：
MeerKAT发现灯塔星云中粒子逃逸并照亮周围磁场的无线电条纹，揭示了高能轻子释放机制及磁场特性。
摘要：
弓形激波脉冲星风星云是研究相对论性脉冲星风动力学及其转化为高能宇宙射线轻子机制的重要来源。灯塔星云是一种这样的天体，以其高速脉冲星和长而偏移的X射线喷流而闻名，后者被认为是最高能粒子的特定逃逸通道。我们旨在更好地了解非热粒子的大部分如何释放到星际介质中。我们专注于GHz无线电观测，这些观测探测的是能量较低但数量多且寿命长的粒子，从而提供逃逸过程长期发展的图景。我们分析了MeerKAT在0.9-1.7GHz频段的10.5小时观测数据。MeerKAT观测揭示了脉冲星PSR J1101-6101下游的高度结构化同步辐射星云。在距离脉冲星5个天文单位之外检测到彗星状尾部，同时首次观测到多个横向双侧发射条纹系统。未发现偏移X射线喷流的无线电对应物。无线电条纹被解释为偶尔的电荷无关释放，即高能轻子从尾部逃逸到周围介质，这是由于下游流中的动力学不稳定性及重新配置所致。强度分布表明，星云中的大部分粒子内容在几个秒差距范围内释放到周围介质中。一旦逃逸，粒子照亮周围磁场，该磁场的相干长度至少为数个秒差距。条纹的长度和持续时间表明磁 turbulence 的水平较低，可能略高于银河系中平均宇宙射线传输条件。这种约束可能源于自生成的湍流，由共振流不稳定性引起，或者由于前缀恒星的过去活动。
英文摘要：
Bow-shock pulsar wind nebulae are valuable sources for investigating the dynamics of relativistic pulsar winds and the mechanisms by which they produce cosmic-ray leptons at the highest energies. The Lighthouse Nebula is one such object, famous for the high velocity of its pulsar and its long, misaligned X-ray jet, which may provide a specific escape channel for the most energetic particles. We aim to understand how the bulk of non-thermal particles is released into the ISM. We focus on GHz radio observations, which probe lower-energy particles that are dominant in number and long-lived, thus providing a picture of how escape proceeds over long timescales. We analysed MeerKAT and ASKAP observations at 1.28GHz and 0.94GHz, respectively. MeerKAT observations reveal a highly structured synchrotron nebula downstream of the pulsar PSRJ1101-6101. A cometary tail extends beyond 5pc from the pulsar, while we detect multiple two-sided transverse emission streaks for the first time. We detect no radio counterpart of the misaligned X-ray jet, but the spectral index map shows an apparent asymmetry, with the steepest values near the base of the jet. We interpret the radio streaks as the occasional, charge-independent release of energetic leptons from the tail into the surrounding medium, resulting from dynamical instabilities and reconfiguration in the downstream flow. Most of the particle content of the nebula is discharged into the ambient medium within several pc. Escaped particles light up the ambient magnetic field, which appears to have a coherence length of at least a few pc. The length and persistence of the streaks indicate a low level of magnetic turbulence, possibly slightly enhanced with respect to average cosmic-ray transport conditions in the Galaxy. This may result from self-generated turbulence caused by a resonant streaming instability or from past activity of the progenitor star.
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