Gravitational lensing statistics with extragalactic surveys - IV. Joint constraints on lambda(0) and Omega(0) from gravitational lensing statistics and CMB anisotropies

We present constraints on the cosmological constant lambda(0) and the densi ty parameter Omega(0) from joint constraints from the analyses of gravitati onal lensing statistics of the Jo- drell Bank-VLA Astrometric Survey (JVAS) , optical gravitational lens surveys from the literature and CMB anisotropi es. This is the first time that quantitative joint constraints involving le nsing statistics and CMB anisotropies have been presented. Within the assum ptions made, we achieve very tight constraints on both lambda(0) and Omega( 0). These assumptions are cold dark matter models, no tensor components, no reionisation, CMB temperature T-CMB = 2.728 K, number of neutrinos n(nu) = 3, helium abundance Y-HE = 0.246, spectral index n(s) = 1.0, Hubble consta nt H-0 = 68 km s(-1) Mpc(-1), baryonic density Omega(b) = 0.05. All models were normalised to the COBE data and no closed models (k = +1) were compute d. Using the CMB data alone, the best-fit model has lambda(0) = 0.60 and la mbda(0) = 0.34 and at 99% confidence the lower limit on lambda(0) + Omega(0 ) is 0.8. Including constraints from gravitational lensing statistics doesn 't change this significantly, although it does change the allowed region of parameter space. A universe with lambda(0) = 0 is ruled out for any value of Omega(0) at better than 99% confidence using the CMB alone. Combined wit h constraints from lensing statistics, lambda(0) = 0 is also ruled out at b etter than 99% confidence. As the region of parameter space allowed by the CMB is, within our assumpti ons, much smaller than that allowed by lensing statistics, the main result of combining, a the two is to change the range of parameter space allowed b y the CMB along its axis of degeneracy.