A Search for Large-Image-Separation Gravitational Lenses in the JVAS Radio Survey

D. R. Marlow, A. D. McGuinness, P. N. Wilkinson & Phillip Helbig

Gravitational lensing directly measures fluctuations in the gravitational potential along paths to distant objects. Currently, there are no firm examples of radio selected lens systems with image separations >7'', but many with separations <7''. We have made use of the approximately 2500 flat-spectrum radio sources that make up JVAS (the Jodrell Bank VLA Astrometric Survey) (Patnaik et al. 1992 and papers in preparation) to select wide-separation (>6'') gravitational lens candidates. Lensing of flat-spectrum radio sources is relatively easy to recognise since the source structures are point-dominated. In the original JVAS analysis, no attempt was made to look for lenses with separations >6'', so this is a new search. The secondary components will be lensed images or part of the source structure or less probably, simply chance sources nearby.