λ 0 and Ω 0 from Lensing Statistics and Other Methods: Is There a Conflict?
Phillip Helbig, J. F. Marcias-Perez, Althea Wilkinson, Rhodri Huw Davies, Ralf Quast, Christopher S. Kochanek · 2001
Abstract. We discuss the consistency of constraints in the λ0-Ω0 plane from gravitational lensing statistics, the m-z relation for type Ia super-novae and CMB anisotropies, based on our own (published or unpub-lished) work and results from the literature. Recently, several authors, (e.g. Perlmutter et al. 1999, Riess et al 1998, Lineweaver 1998) have made the claim that current observational data provide evidence for a positive cosmological constant λ0. This is based mainly on the m-z relation for type Ia supernovae or on CMB anisotropies; although joint constraints from more than one cosmological test also point in this direction (e.g. Ostriker & Steinhardt 1995, Turner 1996, Bagla et al. 1996, Krauss 1998), taken at face value, either the supernovae or CMB data alone suggest the pres-ence of a positive cosmological constant. On the other hand, gravitational lensing statistics (e.g. Kochanek 1996, Falco et al. 1998) has often been seen as setting tight upper limits on the cosmo-logical constant, perhaps even to the point of being in conflict with the ‘cosmic