Paper detail

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.