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The influence of a thermal plasma on synchrotron radiation†

Published online by Cambridge University Press:  09 March 2009

A. Crusius
A. Crusius
Affiliation:
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-5300 Bonn 1, F.R.G.
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Abstract

The synchrotron emission from relativistic electrons in a thermal plasma with large-scale random magnetic fields is considered. In this case, the spectral synchrotron power of a single electron can be given in closed form allowing exact analytical expressions for the synchrotron emissivity, absorption coefficient, intensity and total energy loss of particles to be derived. The influence of various physical parameters such as gas density, magnetic field strength, particle's Lorentz factor on the resulting emissivities, intensities and energy loss is discussed in detail. Below the Razin– Tsytovich frequency vR = 20 Hz (ne/l cm−3) (B/l Gauss)−1, the spectral appearance of synchrotron radiation both in the optically thin and thick case is quite different than the vacuum behaviour. Since in the quasar broad line regions, vR is of the order 1011 Hz the suppression of synchrotron radiation may explain why most quasars are radio quiet. Likewise, the necessary physical conditions for the occurrence of synchrotron masering in the optically thick case are given. We obtain optical depth |τ|>1 for compact nonthermal sources. The total energy loss of a single particle is shown to be exponentially reduced at Lorentz factors less than γR = 2·1. 10−3 (ne/1 cm−3)½ (B/1 Gauss)−1.

Type
Research Article
Information
Laser and Particle Beams , Volume 6 , Issue 3 , August 1988 , pp. 421 - 436
Copyright
Copyright © Cambridge University Press 1988

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