Dynamo activities driven by magnetorotational instability and the parker instability in galactic gaseous disks

Mami Machida, Kenji E. Nakamura, Takahiro Kudoh, Takuya Akahori, Yoshiaki Sofue, Ryoji Matsumoto

研究成果: Contribution to journalArticle査読

28 被引用数 (Scopus)

抄録

We carried out global three-dimensional magnetohydrodynamic simulations of dynamo activities in galactic gaseous disks without assuming equatorial symmetry. Numerical results indicate the growth of azimuthal magnetic fields non-symmetric to the equatorial plane. As the magnetorotational instability (MRI) grows, the mean strength of magnetic fields is amplified until the magnetic pressure becomes as large as 10% of the gas pressure. When the local plasma β (=pgas/pmag) becomes less than 5 near the disk surface, magnetic flux escapes from the disk by the Parker instability within one rotation period of the disk. The buoyant escape of coherent magnetic fields drives dynamo activities by generating disk magnetic fields with opposite polarity to satisfy the magnetic flux conservation. The flotation of the azimuthal magnetic flux from the disk and the subsequent amplification of disk magnetic field by the MRI drive quasi-periodic reversal of azimuthal magnetic fields on a timescale of 10 rotation periods. Since the rotation speed decreases with radius, the interval between the reversal of azimuthal magnetic fields increases with radius. The rotation measure computed from the numerical results shows symmetry corresponding to a dipole field.

本文言語英語
論文番号81
ジャーナルAstrophysical Journal
764
1
DOI
出版ステータス出版済み - 2 10 2013

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

フィンガープリント 「Dynamo activities driven by magnetorotational instability and the parker instability in galactic gaseous disks」の研究トピックを掘り下げます。これらがまとまってユニークなフィンガープリントを構成します。

引用スタイル