Spectral ageing: a new age perspective

Abstract

We present an up-to-date critique of the physical basis for the spectral ageing method. We find that the number of cases where this method may be meaningfully applied to deduce the ages of classical double radio sources is small indeed. This critique is much more than merely a re-expression of anxieties about the calibration of spectral ageing (which have been articulated by others in the past).Comment: 9 pages, 3 figures, published in `Particles & Fields in Radio Galaxies', PASP, eds RA Laing & KM Blundel