Narrow-Angle Tail Radio Sources and the Distribution of Galaxy Orbits in Abell Clusters

The distribution of the orientation of the tails of narrow-angle tail (NAT) radio sources can be used to constrain the distribution of galaxy orbits in clusters. The authors present data on the orientations of the tails with respect to the cluster centers of a sample of 70 NATs in Abell clusters. The whole sample as well as subsamples of sources based on projected distance from the cluster center and on cluster morphology are considered. It is found that the distribution of tail angles in NATs is inconsistent with purely radial or circular orbits in all the samples and is consistent with isotropic orbits in the whole sample, in the sample of NATs far from the cluster center, and in the samples of morphologically regular Abell clusters. However, evidence for very radial orbits is found in the sample of NATs near the cluster center.