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Effect of Advected Fields on Accretion Disk Dynamos

Published online by Cambridge University Press:  12 April 2016

Arun V. Mangalam  and
K. Subramanian
Arun V. Mangalam
Affiliation:
Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303-3083
K. Subramanian
Affiliation:
National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Pune, India

Abstract

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We present calculations of favored dynamo modes when advection of ambient magnetic fields onto accretion disks is important. These models are relevant for compact binary systems and young stellar objects and can be extended to active galactic nuclei (AGNs). The dynamo equation, including the standard α-effect, is modified to take into account advected magnetic fields. Vacuum boundary conditions are assumed outside the disk and the dynamo number switches sign across the equatorial plane. For the local steady state problem, critical dynamo numbers for various modes are obtained analytically. Our motivation is to investigate whether the dominant dynamo generation of quadrupolar magnetic fields and accretion of dipolar magnetic fields is likely to lead to particle acceleration in the form of jets. The results shown here are for a particular choice of boundary conditions and geometry of the advected field. Besides examining other choices, we shall calculate growth rates for different modes, and the influence of the initial seed field configuration on the evolution of the magnetic fields in subsequent work.

Subject headings: acceleration of particles — accretion, accretion disks — binaries: close — galaxies: nuclei — MHD — stars: pre-main-sequence

Type
Poster Papers
Information
International Astronomical Union Colloquium , Volume 142: Particle Acceleration Phenomena in Astrophysical Plasmas , 1994 , pp. 963 - 967
Copyright
Copyright © The American Astronomical Society 1994

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