Galactic dynamo and helicity losses through fountain flow

被引:117
|
作者
Shukurov, A [1 ]
Sokoloff, D
Subramanian, K
Brandenburg, A
机构
[1] Univ Newcastle, Sch Math & Stat, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England
[2] Moscow MV Lomonosov State Univ, Dept Phys, Moscow 119992, Russia
[3] Interuniv Ctr Astron & Astrophys, Pune 411007, Maharashtra, India
[4] NORDITA, DK-2100 Copenhagen O, Denmark
关键词
magnetic fields; turbulence; ISM : magnetic fields; galaxies : ISM;
D O I
10.1051/0004-6361:200600011
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Aims. Nonlinear behaviour of galactic dynamos is studied, allowing for magnetic helicity removal by the galactic fountain flow. Methods. A suitable advection speed is estimated, and a one-dimensional mean-field dynamo model with dynamic alpha-effect is explored. Results. It is shown that the galactic fountain flow is efficient in removing magnetic helicity from galactic discs. This alleviates the constraint on the galactic mean-field dynamo re resulting from magnetic helicity conservation and thereby allows the mean magnetic field to saturate at strength comparable to equipartition with the turbulent kinetic energy.
引用
收藏
页码:L33 / L36
页数:4
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