Astron. Astrophys. 344, 721-734 (1999) Gravitational lensing statistics with extragalactic surveysI. A lower limit on the cosmological constant
Ralf Quast^{ 1} and
Phillip Helbig^{ 2}
Received 2 December 1998 / Accepted 14 January 1999 Abstract We reanalyse optical gravitational lens surveys from the literature in order to determine relative probabilities in the - plane, using a softened singular isothermal sphere lens model. In addition, we examine a portion of the - 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 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 , using lens statistics information alone, are respectively -3.17 and 0.3. For a flat universe, these correspond to lower and upper limits on of respectively -1.09 and 0.65. Key words: cosmology: observations cosmology: theory cosmology: gravitational lensing Send offprint requests to: R. Quast Correspondence to: rquast@hs.uni-hamburg.de Contents
© European Southern Observatory (ESO) 1999 Online publication: March 29, 1999 |