Correlation between Peculiar Galaxies and Radio Sources

Abstract

ARP has claimed¹ that more peculiar galaxies than can be statistically expected lie about midway along lines joining close pairs of radio sources. We have investigated the significance of these claims and, although we have found that the observed distribution might occur by chance in only one sky out of a hundred, we nevertheless believe that much of the correlation is caused by (i) observational selection; (ii) non-uniform large-scale distribution of galaxies and radio sources; (iii) normal clustering of galaxies, radio and peculiar included. The importance of the last two points is emphasized by the fact that bright radio sources occur preferentially in regions of the sky with a high density of galaxies².