Cosmological constant and lensing

Gravitational Lensing and Tests of the Cosmological Constant

The case for a flat Cold Dark Matter model with a positive cosmological constant Λ has been recently strongly advocated by some theoreticians. In this paper we give the observers point of view to the light of the most recent observations with a special emphasis on lensing tests. We confirm the apparent cosmic concordance for a flat Universe with ΩΛ close to 0.6 but we note that a low mass densi...

Gravitational lensing statistics and constraints on the cosmological constant revisited

We re-analyze constraints on the cosmological constant that can be obtained by examining the statistics of strong gravitational lensing of distant quasars by intervening galaxies, focusing on on uncertainties in galaxy models (including velocity dispersion, luminosity functions, core radii and magnification bias effects) and on the parameters of the galaxy distribution and luminosity functions....

Cosmological Constant ?

We prove that a class of one-loop partition functions found by Dienes, giving rise to a vanishing cosmological constant to one-loop, cannot be realized by a consistent lattice string. The construction of non-supersymmetric string with a vanishing cosmological constant therefore remains as elusive as ever. We also discuss a new test that any one-loop partition function for a lattice string must ...

Cosmological Applications of Gravitational Lensing

The last decade has seen an enormous increase of activity in the eld of gravitational lensing, mainly driven by improvements of observational capabilities. I will review the basics of gravitational lens theory, just enough to understand the rest of this contribution, and will then concentrate on several of the main applications in cosmology. Cluster lensing, and weak lensing, will constitute th...

Cosmological Applications of Gravitational Lensing