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Dynamical Implications of Diffusive and Convective Cosmic ray Propagation in Galactic Halos

Published online by Cambridge University Press:  03 August 2017

D. Breitschwerdt ,
J.F. Mckenzie  and
H.J. Völk
D. Breitschwerdt
Affiliation:
1MPI für Kernphysik, D-6900 Heidelberg, Postfach 103980, FRG
J.F. Mckenzie
Affiliation:
2MPI für Aeronomie, D-3411 Katlenburg-Lindau, Postfach 20, FRG
H.J. Völk
Affiliation:
1MPI für Kernphysik, D-6900 Heidelberg, Postfach 103980, FRG

Abstract

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On the basis of our present knowledge about Cosmic Ray (CR) propagation, it is argued that galactic halos should mainly consist of two parts, namely a lower region, extending from the disk-halo interface to a few kpc, in which CR diffusion prevails and an upper region, where convection dominates. The upper part is the possible site of galactic wind formation due to the strong coupling of the CRs to the thermal plasma via (mainly outwards propagating) Alfvén waves as a mediator. In the lower halo and also in the disk, the gas will be effectively static, the wave field will be almost random in its direction (due to stochastic gas motions), and the CRs must diffuse through the gas to escape. We present a model that describes both the upper and the lower halo and briefly discuss simple analytic solutions for the diffusion and numerical results for the convection region.

Type
III. Theory and Modelling
Information
Symposium - International Astronomical Union , Volume 144: The Interstellar Disk-Halo Connection in Galaxies , 1991 , pp. 373 - 376
Copyright
Copyright © Kluwer 1991 

References

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