| Project/Area Number |
16K17708
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Particle/Nuclear/Cosmic ray/Astro physics
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| Research Institution | Waseda University |
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Principal Investigator |
Fujisawa Kotaro 早稲田大学, 理工学術院, 日本学術振興会特別研究員 (30732408)
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000)
Fiscal Year 2018: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2017: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2016: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
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| Keywords | マグネター / 磁場進化 / ホール効果 / 両極性拡散 / 中性子星 / 数値計算スキーム / 強磁場の進化と起源 / 宇宙X線 / トロイダル磁場 / 強磁場の起源と進化 |
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| Outline of Final Research Achievements |
The goal of this research was elucidating of origin and evolution of the magnetic fields of a magnetar by modeling various physical processes. Although previous works proposed many physical mechanisms as the origin of the strong magnetic fields of magnetars, we adopted a classical model among them in which magnetic fields come from charged particles. In that case, ambipolar diffusion in the core is the most efficient physical mechanism for the evolution of magnetic fields. We solved equations and evaluated the timescale of the ambipolar diffusion. We found that the timescale of the ambipolar diffusion in the core is affected by the structures of the crustal magnetic field. The boundary condition at the core-crust interface is important to consider the evolution of the magnetic fields.
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| Academic Significance and Societal Importance of the Research Achievements |
本研究では、マグネターの磁場の起源とその進化を明らかにするために、コアにおける両極性拡散のタイムスケールを計算した。これまでの先行研究ではコア磁場のみを交流したものがほとんどであったが、コア・クラスト両方の磁場構造を考えてコア磁場の両極性拡散の働くタイムスケールを計算した。その結果、これまであまり考慮されていなかった、コア・クラスト磁場の境界条件が両極性拡散のタイムスケールに重要な影響を及ぼすことが分かった。
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