| Project/Area Number |
62540176
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Astronomy
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| Research Institution | Ibaraki University |
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Principal Investigator |
YOKOSAWA Masayoshi Ibaraki University, Faculty of Science Assistant Professor, 理学部, 助教授 (30158357)
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| Co-Investigator(Kenkyū-buntansha) |
須藤 靖 茨城大学, 理学部, 助手 (20206569)
田中 靖夫 茨城大学, 教育学部, 教授 (30007520)
石塚 俊久 茨城大学, 理学部, 助教授 (70007558)
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| Project Period (FY) |
1987 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1989: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1988: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1987: ¥700,000 (Direct Cost: ¥700,000)
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| Keywords | Active Galaxy / Black Hole / Energy Extraction / Magnetohydrodynamics / ブラック・ホール / 降着円盤 / 磁気流体波 / 電磁流体 |
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| Research Abstract |
1. Extraction process of black holes spin energy and magnetohydrodynamical structure around a Kerr black hole are studied by an exact nonstationary solution for the variation of magnetic field with a given axially symmetric accretion. Initially homogeneous magnetic field lines are twisted by the frame-dragging effect, thus exerting a torque on a infalling plasma. This hydromagnetic extraction of a black holes spin energy is analyzed on the assumption of equipartition between the magnetic and kinetic energies of a falling plasma. In order to examine the possible structure of the magnetic field formed around the hole we investigate precisely the structure of the nonstationary magnetic field produced by the stationary accretion. The strongly winding field is formed around the event horizon and then the horizon is seen as wrapped by a bundle of magnetic field lines. The evolution of a rotating black hole immersed in a magnetized plasma and electric energy generation caused by the interaction of magnetized infalling plasma with the accretion disk are discussed.
2. In order to make clear the focusing of the energy and momentum by wave motion, the wave propagation of a sound wave were investigated in curved space-time. By using a canonical-type formulation for the hydrodynamical disturbances in accretion disk, the basic properties of sound wave propagation and the numerical calculations of motion of the locus of simultaneous fronts of wave packets were preseted. The sound waves inside the potentials hi-11 converge into the rotation axis of the black hole.
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