Superluminal Motions: The First 100 Sources

Abstract

First results from a large homogeneous superluminal motion survey are presented. The data do not show compelling evidence for the existence of intrinsically different populations of galaxies, BL Lac objects, or quasars. β app in the range 1–5h −1 occur with roughly equal frequency; higher values, up to β app = 10h −1 are rather more scarce than appeared to be the case from earlier work, which evidently concentrated on sources which are not representative of the general population. The β app distribution suggests that there might be a skewed distribution of Lorentz factors over the sample, with a peak at γb ≈ 2h −1 and a tail up to at least γb ≈ 10h −1. There appears to be a clearly rising upper envelope to the β app distribution when plotted as a function of observed 5 GHz luminosity; a combination of source counts and the apparent velocity statistics in a larger sample could provide much insight into the properties of radio jet sources.