Gravitational lensing statistics with extragalactic surveys

Free access article

Issue		Astron. Astrophys. Suppl. Ser. Volume 136, Number 2, April II 1999


Page(s)		297 - 305
DOI		http://dx.doi.org/10.1051/aas:1999467

DOI: 10.1051/aas:1999467

Astron. Astrophys. Suppl. Ser. 136, 297-305

II. Analysis of the Jodrell Bank-VLA Astrometric Survey

P. Helbig¹ - D. Marlow¹ - R. Quast² - P.N. Wilkinson¹ - I.W.A. Browne¹ - L.V.E. Koopmans³

Send offprint request: P. Helbig
Correspondence to: p.helbig@jb.man.ac.uk

1 - University of Manchester, Nuffield Radio Astronomy Laboratories, Jodrell Bank, Macclesfield, Cheshire SK11 9DL, UK
2 - Universität Hamburg, Hamburger Sternwarte, Gojenbergsweg 112, D-21029 Hamburg, Germany
3 - University of Groningen, Kapteyn Astronomical Institute, Postbus 800, NL-9700 AV Groningen, The Netherlands

Received December 2, 1998; accepted January 12, 1999

Abstract:

We present constraints on the cosmological constant $\lambda_{0}$ from gravitational lensing statistics of the Jodrell Bank-VLA Astrometric Survey (JVAS). Although this is the largest gravitational lens survey which has been analysed, cosmological constraints are only comparable to those from optical surveys. This is due to the fact that the median source redshifts of JVAS are lower, which leads to both relatively fewer lenses in the survey and a weaker dependence on the cosmological parameters. Although more approximations have to be made than is the case for optical surveys, the consistency of the results with those from optical gravitational lens surveys and other cosmological tests indicate that this is not a major source of uncertainty in the results. However, joint constraints from a combination of radio and optical data are much tighter. Thus, a similar analysis of the much larger Cosmic Lens All-Sky Survey should provide even tighter constraints on the cosmological constant, especially when combined with data from optical lens surveys.

At 95% confidence, our lower and upper limits on $\lambda_{0}-\Omega_{0}$ , using the JVAS lensing statistics information alone, are respectively -2.69 and 0.68. For a flat universe, these correspond to lower and upper limits on $\lambda_{0}$ of respectively -0.85 and 0.84. Using the combination of JVAS lensing statistics and lensing statistics from the literature as discussed in Quast & Helbig (1999) the corresponding $\lambda_{0}~-~\Omega_{0}$ values are -1.78 and 0.27. For a flat universe, these correspond to lower and upper limits on $\lambda_{0}$ of respectively -0.39 and 0.64.

Key words: gravitational lensing -- cosmology: theory -- cosmology: observations

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