An Analysis of the Angular Sizes of Radio Sources

An analysis has been made of the fringe visibilities of 133 sources observed at four baselines between 2 200 λ and 61 100 λ . It is shown that, in this group of sources with flux density $$S \geqslant 12 \times 10^{-26}\enspace \text {w.m}^{-2} \enspace(\text {c/s})^{-1}$$ and galactic latitude $$|b^\text I| \geqslant 12^\circ$$ , 50 per cent are resolved at a baseline greater than about 4 000 λ and 90 per cent are resolved at a baseline greater than about 30 000 λ . These results establish the general scale of the angular size distribution among the hundred brightest sources in the Cambridge 3C catalogue. The results from long baseline observations have been combined with those obtained at the California Institute of Technology with several baselines up to 1 560 λ . It is found that at least 40 per cent of the sources must consist of at least two major separated radiating components. An attempt has been made to estimate the characteristic linear size, surface brightness, luminosity and distance of the sources in terms of two cosmological models.