磁星暴发活跃期的观测性质和辐射机制的研究

Magnetar is a group of pulsars with extremely strong magnetic field. They are a unique laboratory to unveil the physics under the extreme conditions which cannot be constructed on our planet. Due to their special nature, the development of the theoretical and simulation study is very slow and difficult. Right now, this field is still mainly motivated by observations. Most information we have about magnetars came from their burst activities. The energetic magnetar bursts/flares exceed the Eddington luminosity by several magnitudes, and last from sub-second to seconds. Sometimes, an outburst of the magnetar persistent emission follows the burst activity. The X-ray luminosity can be ten times brighter than its quiescent level, and the spectral and timing properties may also change. Under the magnetar model the burst activities may due to the neutron star quack or the reconnection of magnetic field lines. However, these models only draw a big picture of the source, none of them can detailed explain or model magnetar emission properties, especially those personalized behavior. In this three-year project, we will use observations from international and Chinese high energy satellites to understand emission mechanisms of magnetar. We propose following sub-projects: (1) expand magnetar sample and systematically study the burst temporal and spectral properties; (2) study the trigger and emission mechanism of magnetar bursts; (3) systematically study the persistent emission above 10 keV of magnetars in order to understand the emission mechanism behind; (4) unveil the connection between short bursts and long outbursts to have a full picture of the magnetar active episode.

强磁场脉冲星（磁星）具有极强的磁场和引力场，是宇宙中独特的研究极端物理规律的实验室。磁星的暴发活动是探究这类小样本天体最主要的渠道。磁星暴发超过爱丁顿光度数个量级，持续几百毫秒到几秒。伴随部分暴发，磁星的持续辐射亮度在很长一段时间内增亮几倍至几十倍，同时能谱和时变性质均可改变。在磁星模型框架下有一些粗略的图像可以解释暴发活动，如星震和磁重连效应。但暴发的观测性质（尤其一些个体化的性质）与物理机制的具体描述还是脱节的。本项目利用国内外高能天文卫星数据，将从以下几方面进一步揭开磁星暴发辐射的谜团：（1）扩充磁星和磁星暴发样本；（2）磁星短暴发触发和辐射机制；（3）磁星高能持续辐射的性质；（4）磁星暴发活跃期的内在行为关联和整体性质。

极强磁场中子星，即磁星，不仅是极端物理的天然实验室，也是目前唯一被认证的快速射电暴的对应体。本项目在研期间主要研究了磁星爆发辐射的性质、对比研究不同活跃期的爆发辐射性质演化。我们详细分析了磁星SGR J1935+2154历年爆发的性质及演化，对爆发的辐射区性质和辐射机制进行了讨论。研究成果分别以三篇文章的形式发表在Astrophysical Journal和Astrophysical Journal Letter上。我们进一步研究磁星爆发与快速射电暴的相关性。我们的研究发现来自磁星的FRB与能谱性质独特的X射线爆发成协，限制来自磁星FRB的辐射区性质，还可以对磁星爆发事件的触发机制模型提供佐证。另一方面我们利用FAST观测给出了磁星典型X射线爆发时的射电流量上限，揭示了磁星爆发与FRB的弱相关性，对理解磁星产生FRB的物理做出了重要贡献。这一成果发表在Nature杂志。