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Published May 21, 1998 | Published
Journal Article Open

B0712+472: a new radio four-image gravitational lens


A new four-image gravitational lens system, B0712+472, has been discovered during the Cosmic Lens All-Sky Survey. This system consists of four flat-spectrum radio images that are also seen on a Hubble Space Telescope (HST) image, together with the lensing galaxy. We present MERLIN, VLA and VLBA maps and WHT spectra of the system as well as the HST images. The light distribution of the lensing galaxy is highly elongated and so too is the mass distribution deduced from modelling. We suggest a redshift of ∼1.33 for the lensed object; the lens redshift will require further investigation. The discovery of this new system further increases the ratio of four-image to two-image lens systems currently known, exacerbating problems of required ellipticity of matter distributions in lensing galaxies.

Additional Information

© 1998 RAS. Accepted 1997 November 3. Received 1997 August 27; in original form 1997 April 18. MERLIN is operated as a National Facility by NRAL, University of Manchester, on behalf of the UK Particle Physics & Astronomy Research Council. The William Herschel Telescope is operated by the Royal Greenwich Observatory on the island of La Palma at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. The VLA and VLBA are operated by Associated Universities for Research in Astronomy Inc. on behalf of the National Science Foundation. This research used observations with the Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by Associated Universities for Research in Astronomy Inc. under NASA contract NAS5-26555. One spectrum was obtained as part of the La Palma telescopes international time project 'The radio universe at low flux density levels' allocated by the Comite Cientifico Internacional, and the other by the WHT service programme. All spectra were processed using the National Optical Astronomy Observatories IRAF package. We thank the pulsar group at Jodrell Bank for the use of their computing facilities. This research was supported by European Commission, TMR Programme, Research Network Contract ERBFMRXCT96-0034 'CERES'.

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