The Gravitational Lens System B1422+231: Dark Matter, Superluminal Expansion and the Hubble Constant

A gravitational lens model of the radio quasar B1422+231 is presented which can account for the image arrangement and approximately for the relative magnifications. The locations of the principal lensing mass and a more distant secondary mass concentration were predicted and subsequently luminous galaxies were found at these locations. This argues against the existence of substantial numbers of “dark” galaxies. The model suggests that if the compact radio source is intrinsically superluminal then the observed component motions may be as large as ∼ 100c with image B moving in the opposite direction to images A and C. The prospects for a measuring the Hubble constant from a model incorporating lens galaxy locations, compact radio source expansion speeds and radio time delays, if and when these are measured, are briefly assessed.