Gravitational lensing statistics with extragalactic surveys. I. A lower limit on the cosmological constant
Abstract
Description
We reanalyse optical gravitational lens surveys from the literature in order to determine relative probabilities in the $λ_{0}$-$Ω_{0}$ plane, using a softened singular isothermal sphere lens model. In addition, we examine a portion of the $λ_{0}$-$Ω_{0}$ plane which includes all viable cosmological models; this is vital for comparison with other cosmological tests. The results are, within the errors, consistent with those of more specialised analyses, such as those concerning upper limits on $λ_{0}$ in a flat universe. We note that gravitational lensing statistics can provide a quite robust LOWER limit on the cosmological constant as well, which could prove important in confirming current claims of a positive cosmological constant. At 95% confidence, our lower and upper limits on $λ_{0}-Ω_{0}$, using lens statistics information alone, are respectively -3.17 and 0.3. For a flat universe, these correspond to lower and upper limits on $λ_{0}$ of respectively -1.09 and 0.65.
LaTeX, 16 pages, 23 PostScript files in 10 figures. Paper version available on request. Data available from http://multivac.jb.man.ac.uk:8000/ceres/data_from_papers/papers.html or http://gladia.astro.rug.nl:8000/ceres/data_from_papers/papers.html
LaTeX, 16 pages, 23 PostScript files in 10 figures. Paper version available on request. Data available from http://multivac.jb.man.ac.uk:8000/ceres/data_from_papers/papers.html or http://gladia.astro.rug.nl:8000/ceres/data_from_papers/papers.html