D-123 銀河ダイナモ機構の大局的 3 次元磁気流体数値実験

概要

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The galactic dynamo theory has been studied over many years as the mechanism of amplification and maintenance of large scale magnetic fields in galaxies. We carried out global three-dimensional magnetohydrodynamic (MHD) simulations of galactic gas disks to investigate how the galactic magnetic fields are amplified and maintained. We adopt steady axially symmetric gravitational potential. As the initial condition, we assume a hot rotating torus threaded by weak azimuthal magnetic fields. Numerical results indieate that in differentially rotating galactic gas disks, magnetic fields are amplified due to Magnetorotational instability and that magnetic turbulence develops. After the amplification of magnetic fields saturate, the disk magnetic field is maintained for 6 billion years. We computed the spacially averaged values of the component of dynamo α perpendicular to the equatorial plane. Numerical results indicate that the dynamo α is spatially inhomogenious.
日本流体力学会の論文
2003-07-28