On the Angular Distribution of Complete Samples of Bright Quasi-Stellar and Unidentified Radio Sources

Abstract

Using a variant of Fisher's method of aralysis of dispersion on a sphere, a study is made of the angular distribution on the sky of various complete samples of unidentified and quasi-stellar radio sources (QSRs) from the 3C and Parkes catalogues. Samples chosen by redshift, apparent optical brightness, and radio dimension do not show evidence of gross departures from a uniform random distribution. Statistical analysis does not corfirm Arp' s suggested association of optically faint QSRs with the brighter galaxies in the Shapley- Ames catalogue. However, evidence is found of a strong anisottopy in the distribution of 3C blank field radio sources. In addition; the bright compact QSRs with flat radiospectral indices are anisotropically distributed along the axis of the Local Supercluster at high galactic latitudes. This class of QSRs shows unusual optical and radio variability, and associations with Arp' s peculiar galaxies and Zwicky clusters of galaxies. Thus difficulties may arise in the interpretation of a composite log N--log S curve of radio sources, because its validity depends on assumptions of spatial homogeneity and isotropy at all flux levels. (auth)