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Propagation-induced Circular Polarisation in Synchrotron Sources

Published online by Cambridge University Press:  05 March 2013

Malcolm Kennett
Affiliation:
Research Centre for Theoretical Astrophysics, School of Physics, University of Sydney, NSW 2006, Australia; kennett@physics.usyd.edu.au
Don Melrose
Affiliation:
Research Centre for Theoretical Astrophysics, School of Physics, University of Sydney, NSW 2006, Australia; d.melrose@physics.usyd.edu.au
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Abstract

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The small degree of circular polarisation observed in some synchrotron sources has a frequency dependence that is not consistent with simple predictions based on the intrinsic circular polarisation of synchrotron emission. The suggestion is explored that the circular polarisation arises as a propagation effect within the source. The physical basis of this alternative mechanism is the fact that the natural wave modes of a synchrotron emitting gas are linearly polarised, allowing partial conversion of linear into circular polarisation as in a quarter-wave plate. A relativistic rotation measure (RRM) is defined to characterise the magnitude of this effect.

Type
Research Article
Copyright
Copyright © Astronomical Society of Australia 1998

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