Spectral ageing in a sample of 14 high-luminosity double radio sources

Abstract

We use multifrequency observations of a sample of 14 high-luminosity 3C double radio sources in a discussion of their structures and spectral properties. The observations were made with the VLA at 1.4, 5 and 15 GHz and have resolutions of 0.4 or 1.2 arcsec. We interpret the spectra in terms of the ageing of the electron population, as in the related study by Alexander & Leahy. The hotspots always have the youngest population of electrons, and the apparent ages increase away from the hotspot, even in those cases where the diffuse emission extends perpendicular to the source axis or directly away from the nucleus.