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Particle Acceleration in electrically non-neutral magnetic neutral sheet and application in high energy astrophysics

电非中性磁中性片中的粒子加速及其在高能天体物理中的应用

基本信息

批准号：
19540235
负责人：
SHIBATA Shinpei
金额：
$ 2.91万
依托单位：
Yamagata University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2007
资助国家：
日本
起止时间：
2007 至 2009
项目状态：
已结题

项目摘要

Previous study on the magnetic neutral sheet and the particle asscerelation in it has been on cases for electric quasi-neutral plasma. In this study electrically non-neutral cases have been considered. We attempted to clarify the mechanism of particle acceleration in electrically non-neutral current sheet. This study may resole long standing so called sigma-problem.We have found quasi-periodic magnetic reconnection in the magnetic neutral sheet at the Y-point by using a newly developed particle-in-cell scheme (presented at annual meeting of astronomical society of Japan in 2009). This dissipation may explain the gamma-ray raridation from the pulsars observed Fermi gamma-ray telescope.In addition to this, we examine the X-ray data which may caused by synchrotron dissipation and pitch angle scattering. In particular, we have reproduced the hard X-ray image which showd double peaked image. We find that if high energy particles are dominated by ones with small pitch angles, then observation is reproduced well. This contradicts with the standard understanding of the post shock plasma.It is shown for the first time that the magnetic reconnection takes palace in the termination shock of the pulsar wind.It is suggested that the kinetic energy dominant wind is not produced in the relativistic centrifugal wind. Therefore, the sigma-problem cannot be resolved. We rather suggest that the magnetic reconnection in the shock convert the kinetic energy to thermal one so that there is no sigma-problem, i.e., the wind is not dominated by the plasma kinetic energy in bulk motion.

以往对磁中性片及其粒子加速度的研究主要集中在准中性电等离子体的情况下。本研究考虑了电非中性的情况。我们试图阐明非中性电流片中粒子加速的机理。这项研究可能解决长期存在的所谓西格玛问题。我们利用新提出的粒子单元方案（在2009年日本天文学会年会上提出）在y点的磁中性片上发现了准周期磁重联。这种耗散可以解释费米伽玛射线望远镜观测到的脉冲星的伽玛射线辐射。此外，我们还研究了可能由同步加速器耗散和俯仰角散射引起的x射线数据。特别地，我们复制了硬x射线图像，显示双峰图像。我们发现，如果高能粒子以小俯仰角粒子为主，那么观测结果可以很好地再现。这与对冲击后等离子体的标准理解相矛盾。首次证明了磁重联在脉冲星风的终止激波中起主导作用。这表明，在相对论性离心风中并不产生动能优势风。因此，西格玛问题无法解决。我们建议激波中的磁重联将动能转化为热能，这样就不存在sigma问题，即风不受体运动中等离子体动能的支配。