[en] High-resolution MERLIN observations of a newly discovered four-image gravitational lens system, B0128+437, are presented. The system was found after a careful re-analysis of the entire CLASS data set. The MERLIN observations resolve four components in a characteristic quadruple-image configuration; the maximum image separation is 542mas and the total flux density is 48mJy at 5GHz. A best-fitting lens model with a singular isothermal ellipsoid results in large errors in the image positions. A significantly improved fit is obtained after the addition of a shear component, suggesting that the lensing system is more complex and may consist of multiple deflectors. The integrated radio spectrum of the background source indicates that it is a gigahertz peaked spectrum source. It may therefore be possible to resolve structure within the radio images with deep VLBI observations and thus to constrain the lensing mass distribution better.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Phillips, P. M.; University of Manchester, Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL
Norbury, M. A.; University of Manchester, Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL
Koopmans, L. V. E.; University of Manchester, Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL ; Kapteyn Astronomical Institute, Postbus 800, NL-9700 AV Groningen, the Netherlands
Browne, I. W. A.; University of Manchester, Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL
Jackson, N. J.; University of Manchester, Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL
Wilkinson, P. N.; University of Manchester, Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL
Biggs, A. D.; University of Manchester, Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL
Blandford, R. D.; California Institute of Technology, Pasadena, CA 91125, USA
de Bruyn, A. G.; Kapteyn Astronomical Institute, Postbus 800, NL-9700 AV Groningen, the Netherlands ; Netherlands Foundation for Research in Astronomy, Postbus 2, NL-7990 AA Dwingeloo, the Netherlands
Fassnacht, C. D.; National Radio Astronomy Observatory, PO Box 0, Socorro, NM 87801, USA
Helbig, Phillip ; Kapteyn Astronomical Institute, Postbus 800, NL-9700 AV Groningen, the Netherlands
Mao, S.; University of Manchester, Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL
Marlow, D. R.; Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104, USA
Myers, S. T.; National Radio Astronomy Observatory, PO Box 0, Socorro, NM 87801, USA
Pearson, T. J.; California Institute of Technology, Pasadena, CA 91125, USA
Readhead, A. C. S.; California Institute of Technology, Pasadena, CA 91125, USA
Rusin, D.; Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104, USA
Xanthopoulos, E.; University of Manchester, Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL)
