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8.1. Magnetic phenomena in galactic nuclei

Published online by Cambridge University Press:  25 May 2016

Mark Morris
Mark Morris*
Affiliation:
Department of Physics and Astronomy, UCLA, Box 951562, Los Angeles, California 90095-1562, USA

Abstract

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The magnetic environment of the Galactic nucleus contrasts sharply with that of the Galactic disk. The inner few hundred parsecs of our Galaxy appear to be dominated by a strong (~milligauss) and uniform dipole field which dominates the pressure within the central intercloud medium. An attractive hypothesis for the origin of the central vertical field is that it results from the concentration of protogalactic field by radial inflow of gas throughout the Galaxy's lifetime. The predominant orientation of the magnetic field within dense molecular clouds is parallel to the galactic plane, which can be understood in terms of the strong tidal shear to which these clouds are subjected. The contrasting geometries of the cloud and intercloud fields allow for magnetic field line reconnection at cloud surfaces, which, under the right circumstances, could produce the relativistic electrons which delineate the nonthermal radio filaments near the Galactic center with their synchrotron emission. The characteristics of the Galactic center “magnetosphere” should be generalizable to all gas-rich spiral galaxies. Inadequate spatial resolution currently prevents us from exploring magnetic fields in other galactic nuclei to the same depth as in the Galactic center, but existing evidence is consistent with similar magnetic geometries elsewhere.

Type
Part II. Nuclear Interstellar Medium
Information
Symposium - International Astronomical Union , Volume 184: The Central Regions of the Galaxy and Galaxies , 1998 , pp. 331 - 340
Copyright
Copyright © Kluwer 1998 

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