Radio Sources having Spectra with a Low Frequency Cut-off

Abstract

The four mechanisms that can be responsible for a cut-off in the spectrum of the radio frequency radiation from radio sources have been examined. The results of this analysis have been applied to fourteen sources in the 3C list, whose spectra have been shown to be curved by recent observations at 38 Mc/s. Useful limits are derived for the field strength and other parameters of these sources.