2007 Fiscal Year Final Research Report Summary
Study of Nonlinear Shock Acceleration Process : Origin of Cosmic Ray Anomalous Composition
| Project/Area Number |
17540233
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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 |
Particle/Nuclear/Cosmic ray/Astro physics
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| Research Institution | Tokyo Institute of Technology (2006-2007)
The University of Tokyo (2005) |
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Principal Investigator |
TERASAWA Toshio Tokyo Institute of Technology, Interactive Research Center of Science, Professor (30134662)
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| Co-Investigator(Kenkyū-buntansha) |
HADA Toru Kyushu University, Department of Earth System Science and Technology, Associate Professor (30218490)
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| Project Period (FY) |
2005 – 2007
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| Keywords | cosmic rays / diffusive shock acceleration / composition anomaly / cosmic dust / nonlinear effect / solar flares / Alfen waves / sound waves |
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| Research Abstract |
We have studied nonlinear diffusive shock acceleration process for cosmic ray particles. (1) Importance of coherent property of large amplitude Alfven waves. (2) New theoretical result for large amplitude Alfven waves in plasmas of beta=1. (3) Under the coexistence of Alfven and sound waves, the shock compression ratio and the energy spectrum of accelerated particle are substantially modified. (4) There has been theoretical arguments that the cosmic ray composition anomaly is caused by the preferential acceleration of interstellar dust particles in the shock acceleration region, so that the accurate estimation of interstellar dust particles is crucial for the confirmation/rejection of these theoretical models. To refine the estimation of interstellar dust flux, which is needed to understand the origin of cosmic ray composition anomaly, we have obtained quantitative estimation of the uncertainty in the radar method for the interstellar dust detection. (5) By extending the radar method for dust detection, we have developed a new radar method for the observation of extensive air showers produced by highest energy cosmic rays. (6) We have obtained a new evidence of cosmic-ray-mediated shock feature at the interplanetary shock ejected from an X17 solar flare on 7 September 2005. We have also succeeded in reducing the estimation error for the shock angle determination to 30% of the previous estimations. (7) We have made a quantitative study of the particle acceleration process at interplanetary slow shocks.
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