快速射电暴爆发机制的研究

Rapid progresses have been made in the field of fast radio bursts (FRB) since the first event (FRB 010724) was reported by Lorimer et al. in 2007. Currently, 30 FRBs have been detected, among which only one source was found to burst repeatedly. For other FRBs, none of them is found to be repeative, and also no counterparts in other bands have been found to be associated with them. Tens of models have been proposed to explain FRBs, but none of them is widely accepted by the whole community. The bursting mechanism has been a big enigma in the field of FRBs. The applicant has been engaged in the study of high energy astrophysics for more than twenty years. He has published 102 SCI papers, which were cited by other authors by more than 1300 times. He has also published a few important papers on FRBs. For example, he derived the intensity distrubution function for FRBs, and also suggested that FRBs could be produced by collisions between asteroids and neutron stars. In this project, the applicant will study FRBs by method of statistics. The observed events will be classified by considering more physical criterions. The physical conditions near the central engine and along the line of sight will be probed by carefully examing polarization observations. The time delay at different observing frequency will be used to test the principle of equivalence and also the static mass of photons. New mechanisms for FRBs will be exploed. Especially, the possibility that FRBs could be produced by strange quark stars will be studied.

自Lorimer等人2007年报告第一个快速射电暴以来，该领域发展十分迅速。目前已经观测到30个快速射电暴，但只有一个源确认可重复爆发，其它源则都既未被观测到重复爆发现象，也未发现射电或其它波段的对应体。人们提出了数十种模型来解释快速射电暴的产生过程，但至今尚没有任何一个理论得到广泛认可，因此快速射电暴的爆发机制成为亟待解决的一大谜团。申请人长期从事高能天体物理研究，已正式发表SCI论文102篇，论文被他引1300余篇次。快速射电暴领域，申请人也已取得一批重要成果，包括给出了快速射电暴的强度分布函数、提出了小行星-中子星碰撞产生快速射电暴的新机制等等。本项目中我们将对快速射电暴样本展开统计分析和分类研究，利用它们的偏振观测研究辐射区和传播路径上的物理状态，利用其不同频率的到达时间检验等效原理和限制光子静止质量，并研究快速射电暴的爆发机制，包括研究奇异夸克星产生快速射电暴的可能性等等。

快速射电暴是一个新兴的高能天体物理研究领域，近年来国际上新进展不断涌现：发现了重复爆发源、探测到的事例数目爆炸性增长、观测到部分暴源的寄主星系、测出了部分暴源的红移和距离、测量了偏振及其演化特征、观测到高度活跃的重复爆发源、发现了部分重复暴源爆发的周期性、观测到银河系内来自磁陀星的快速射电暴并探测到相伴的X射线暴等等。至今人们已经发现了近千个快速射电暴源，其中重复源有数十个，部分活跃的重复暴源发生了上千次爆发活动。学者们对该现象的认识总体上已有了很大提升，但一些根本性的问题仍远未厘清。本项目围绕快速射电暴的爆发机制这一核心问题开展研究，取得了一系列有显示度的成果：（1）针对与河内磁陀星SGR 1935+2154关联并伴随着短时标硬X射线暴的快速射电暴FRB 200428事件，提出了小行星-中子星碰撞模型，合理解释了其主要观测特征，包括双脉冲结构、持续时间及硬X-射线暴能谱等等；（2）提出了奇异夸克星吸积导致极冠区壳层坍缩产生周期性重复快速射电暴的全新模型：在包含奇异星的密近双星系统中，伴星的物质会被剥离并流向奇异星极冠区，该吸积过程受到流体的热-粘滞不稳定性调制，很自然地产生周期性重复快速射电暴现象。适当选取粘滞参数和吸积率时，该模型可以自然地解释FRB 180916的活跃期和宁静期行为；（3）研究了在高椭率轨道上围绕中子星运动的行星，发现当近星点小于2.7倍潮汐瓦解半径时，行星每次经过近星点都会被潮汐力部分瓦解产生碎片，碎片与磁层作用可产生重复快速射电暴；（4）对重复暴源的大量爆发进行了统计研究，发现了它们由外部过程触发的证据；（5）从多个角度对奇异夸克星的性质进行了深入研究，为揭示快速射电暴的中心引擎提供了重要线索。项目团队共发表SCI论文30篇，所取得的成果对理解快速射电暴的爆发过程有重要学术价值，得到国内外学者广泛关注和引用。项目组积极对取得的科研成果进行科普宣传，社会反响良好。