D. R. Marlow

Constraints on cosmological parameters from the analysis of the Cosmic Lens All Sky Survey radio-selected gravitational lens statistics

We derive constraints on cosmological parameters and the properties of the lensing galaxies from gravitational lens statistics based on the final Cosmic Lens All Sky Survey data. For a flat universe with a classical cosmological constant, we find that the present matter fraction of the critical density is Omega(m)=0.31(+0.27)(-0.14) (68%)+0.12-0.10 (syst). For a flat universe with a constant equation of state for dark energy w=p(x)(pressure)/rho(x)(energy density), we find w<-0.55(+0.18)(-0.11) (68%).

High-resolution observations and mass modelling of the CLASS gravitational lens B1152+199

We present a series of high-resolution radio and optical observations of the CLASS gravitational lens system B1152+199 obtained with the Multi-Element Radio-Linked Interferometer Network, Very Long Baseline Array and Hubble Space Telescope. Based on the milliarcsecond-scale substructure of the lensed radio components and precise optical astrometry for the lensing galaxy, we construct models for the system and place constraints on the galaxy mass profile. For a single galaxy model with surface mass density Σ(r)∝r−β, we find that 0.95β1.21 at 2σ confidence. Including a second deflector to represent a possible satellite galaxy of the primary lens leads to slightly steeper mass profiles.

Gravitational lensing statistics with extragalactic surveys II. Analysis of the Jodrell Bank-VLA Astrometric Survey

Published in: Astron. Astrophys. Suppl. Ser. 136 (1999) no. 2, pp.297-305 citations recorded in [Science Citation Index] Abstract: We present constraints on the cosmological constant

A complete infrared Einstein ring in the gravitational lens system B1938+666

lambda_{0}

A new radio double lens from CLASS: B1127‡385

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

The new gravitational lens system B1030+074

lambda_{0}-Omega_{0}

NICMOS and VLBA observations of the gravitational lens system B1933+503

, 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 lensing statistics and lensing statistics from the literature as discussed in Quast & Helbig (Paper I) the corresponding

The JVAS/Class Gravitational Lens Surveys

lambda_{0}-Omega_{0}

Constraining the Value of the Cosmological Constant Using JVAS/Class Lensing Statistics

values are -1.78 and 0.27. For a flat universe, these correspond to lower and upper limits on

CLASS B0445+123 : a new two-image gravitational lens system

lambda_{0}