Tsytovitch-Razin Effect

If thermal plasma is present in the emitting region, both the synchrotron radiation intensity and the degree of polarization are reduced.

The presence of a thermal plasma in the emitting region means that the refractive index of the medium is less than unity and the phase velocity of electromagnetic waves is greater than $c$. As a result, synchrotron radiation is suppressed at frequencies where the refractive index becomes significantly less than 1. This is often called Tsytovich-Razin effect. The consequence is a low-frequency cutoff near

$$\rm { {\nu_{R}} = {{4 c n e} \over {3 B_{\bot}}} = {{2\nu_{p... ... \nu_{0}}} \sim {{2 \times 10^{-5} n} \over {B_{\bot}}} MHz}$$ (5..8)

where $B_{\bot}$ is in gauss and n is the number of electron per $cm^{-3}$ and $\nu_{p} = [(ne^2)/(\pi m)]^{1/2}$ is the plasma frequency. (Ref : C.J. Salter, R.L.Brown, "Galactic non-thermal continuum emission", Galactic and extragalactic radio astronomy, eds by K.I.Kellermann, G.L.Verschuur.)