Measuring Cosmological Parameters with the JVAS and CLASS Gravitational Lens Surveys

Creators: Helbig, P.; Blandford, R. D.; Browne, I. W. A.; de Bruyn, A. G.; Fassnacht, C. D.; Jackson, N.; Koopmans, L. V. E.; Macías-Pérez, J. F.; Marlow, D. R.; Myers, S. T.; Quast, R.; Rusin, D.; Wilkinson, P. N.; Xanthopoulos, E.

Abstract

The JVAS (Jodrell Bank-VLA Astrometric Survey) and CLASS (Cosmic Lens All-Sky Survey) are well-defined surveys containing about ten thousand flat-spectrum radio sources. For many reasons, flat-spectrum radio sources are particularly well-suited as a population from which one can obtain unbiased samples of gravitational lenses. These are by far the largest gravitational (macro)lens surveys, and particular attention was paid to constructing a cleanly-defined sample for the survey itself and for the underlying luminosity function. Here we present the constraints on cosmological parameters, particularly the cosmological constant, derived from JVAS and combine them with constraints from optical gravitational lens surveys, 'direct' measurements of Ω_0, H_0 and the age of the universe, and constraints derived from CMB anisotropies, before putting this final result into the context of the latest results from other, independent cosmological tests.

Additional Information

This research was supported in part by the European Commission, TMR Programme, Research Network Contract ERBFMRXCT96-0034 'CERES'. CERES, standing for the Consortium for European Research on Extragalactic Surveys, is an EU TMR Network, coordinated by Ian Browne at Jodrell Bank, and involving the Nuffield Radio Astronomy Laboratories of the Universtity of Manchester at Jodrell Bank, the Institute of Astronomy of the University of Cambridge, The Kapteyn Astronomical Institute of the University of Groningen, the Netherlands Foundation for Research in Astronomy at Dwingeloo, the University of Bologna and the University of Portugal. One of the main goals of CERES is the use of the JVAS and CLASS surveys for research in gravitational lensing. We thank our collaborators in the JVAS, CJF and CLASS surveys for useful discussions and for providing data in advance of publication and many colleagues at Jodrell Bank for helpful comments and suggestions. We also thank John Meaburn and Anthony Holloway at the Department of Astronomy in Manchester and the staff at Manchester Computing for providing us with additional computational resources. RQ is grateful to the CERES collaboration for making possible a visit to Jodrell Bank where part of this work was done.

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