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Basic Properties of Swing-Excitation Mechanism

Published online by Cambridge University Press:  19 July 2016

M. Chiba  and
M. Hanasz
M. Chiba
Affiliation:
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, W-5300 Bonn, Germany
M. Hanasz
Affiliation:
Institute of Astronomy, N. Copernicus University, ul. Chopina 12/18 87-100 Toruń, Poland

Abstract

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We describe the basic process of coupling between dynamo and density waves in galaxies. The growth rate of magnetic field as a result of coupling is derived, applying the method of multiple time scales to the marginal state of disk dynamo. It is shown that the 1st-order resonance in a perturbation of density and thus the linear swing excitation, is possible. Moreover, the growth rate of magnetic field is always positive and does not depend on the initial phase difference between the magnetic and density waves. Both the numerical and analytical calculations show that ω = 2ω0 (ω: density-wave freq., ω0: dynamo freq.) is still the best condition for resonance due to the linear effect of swing excitation.

Keywords

Galactic Magnetic FieldsSpiral ArmsResonance
Type
8. Magnetic Fields in Galaxies: Dynamo Theory
Information
Symposium - International Astronomical Union , Volume 157: The Cosmic Dynamo , 1993 , pp. 375 - 380
Copyright
Copyright © Kluwer 1993 

References

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