The motion of magnetic fronts in spiral galaxies

We study the nonlinear asymptotic thin disc approximation to the mean field dynamo equations, as applicable to spiral galaxies. The circumstances in which sharp magnetic field structures (fronts) can propagate radially are investigated, and an expression for the speed of propagation derived. We find that the speed of an interior front is proportional to η/R* (where η is the diffusivity and R* the galactic radius), whereas an exterior front moves with speed of order √γη, where γ is the local growth rate of the dynamo. Numerical simulations are presented, that agree well with our asymptotic results. Further, we perform numerical experiments using the 'no-z' approximation for thin disc dynamos, and show that the propagation of magnetic fronts in this approximation can also be understood in terms of our asymptotic results.

Авторы
Moss D.1 , Petrov A. 2 , Sokoloff D.3
Редакторы
-
Издательство
-
Номер выпуска
2
Язык
Английский
Страницы
129-148
Статус
Опубликовано
Подразделение
-
DOI
-
Номер
-
Том
92
Год
2000
Организации
  • 1 Mathematics Department, Manchester University, Manchester, M13 9PL, United Kingdom
  • 2 People's Friendship University, Ordzonikidze, 3, Moscow, 117923, Russian Federation
  • 3 Department of Physics, Moscow State University, Moscow, 117588, Russian Federation
Ключевые слова
Galactic dynamo; Magnetic fronts; Seed field; Sharp structures
Дата создания
19.10.2018
Дата изменения
19.10.2018
Постоянная ссылка
https://repository.rudn.ru/ru/records/article/record/417/