Cosmological Constraints From the 100 Square Degree Weak Lensing Survey

• Main Authors: Benjamin, Jonathan, Heymans, Catherine, Semboloni, Elisabetta, Van Waerbeke, Ludovic, Hoekstra, Henk, Erben, Thomas, Gladders, Michael D, Hetterscheidt, Marco, Mellier, Yannick, Yee, H. K. C
• Format: Journal Article
• Language: English
• Published: 22-03-2007
• Subjects: Physics - Astrophysics of Galaxies; Physics - Cosmology and Nongalactic Astrophysics; Physics - Earth and Planetary Astrophysics; Physics - High Energy Astrophysical Phenomena; Physics - Instrumentation and Methods for Astrophysics; Physics - Solar and Stellar Astrophysics
• DOI: 10.48550/arxiv.astro-ph/0703570

Mon.Not.Roy.Astron.Soc.381:702-712,2007 We present a cosmic shear analysis of the 100 square degree weak lensing
survey, combining data from the CFHTLS-Wide, RCS, VIRMOS-DESCART and GaBoDS
surveys. Spanning ~100 square degrees, with a median source redshift z~0.78,
this combined survey allows us to place tight joint constraints on the matter
density parameter Omega_m, and the amplitude of the matter power spectrum
sigma_8, finding sigma_8*(Omega_m/0.24)^0.59 = 0.84+/-0.05. Tables of the
measured shear correlation function and the calculated covariance matrix for
each survey are included.
The accuracy of our results is a marked improvement on previous work owing to
three important differences in our analysis; we correctly account for cosmic
variance errors by including a non-Gaussian contribution estimated from
numerical simulations; we correct the measured shear for a calibration bias as
estimated from simulated data; we model the redshift distribution, n(z), of
each survey from the largest deep photometric redshift catalogue currently
available from the CFHTLS-Deep. This catalogue is randomly sampled to reproduce
the magnitude distribution of each survey with the resulting survey dependent
n(z) parametrised using two different models. While our results are consistent
for the n(z) models tested, we find that our cosmological parameter constraints
depend weakly (at the 5% level) on the inclusion or exclusion of galaxies with
low confidence photometric redshift estimates (z>1.5). These high redshift
galaxies are relatively few in number but contribute a significant weak lensing
signal. It will therefore be important for future weak lensing surveys to
obtain near-infra-red data to reliably determine the number of high redshift
galaxies in cosmic shear analyses.