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Session 59 - Relativistic Astrophysics.
Oral session, Thursday, January 08
A large sample of gravitational lenses is crucial for their use as probes of cosmology and galaxy evolution. Radio surveys have proven to be very effective at finding gravitational lenses. The three large radio searches (MG-VLA, JVAS and CLASS) have between them discovered almost half of the \sim30 known systems with galaxy-sized lenses. Among these are the ``Einstein ring'' systems, in which the background source is a radio lobe, and which can offer many constraints on the lensing mass distribution. Although radio lobes cover a larger fraction of the sky, the great majority of the lensed radio sources are compact. Current searches are not optimized for finding lensed radio lobes, and are missing a potentially large sample of lenses. An efficient way to find Einstein ring systems is to select radio lobes which are superposed on an optical galaxy. We have identified a large sample of radio lobes in the FIRST survey, and used the Cambridge APM to search for optical counterparts. Our initial search has produced \sim900 candidates, and we have proposed to pursue some of these with high-resolution radio observations. We will report on the progress of this project and show a representative selection of candidates.
Program listing for Thursday