2009 Fiscal Year Final Research Report
Particle Acceleration in electrically non-neutral magnetic neutral sheet and application in high energy astrophysics
| Project/Area Number |
19540235
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Astronomy
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| Research Institution | Yamagata University |
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Principal Investigator |
SHIBATA Shinpei Yamagata University, 理学部, 教授 (90187401)
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| Project Period (FY) |
2007 – 2009
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| Keywords | 天文学 / 高エネルギー物理 / プラズマ / ガンマ線天文学 |
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| Research Abstract |
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.
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