2007A&A...468..859H

We present a cosmic shear analysis and data validation of 15 square degree high-quality R-band data of the Garching-Bonn Deep Survey obtained with the Wide Field Imager of the MPG/ESO 2.2m telescope. We measure the two-point shear correlation functions to calculate the aperture mass dispersion. Both statistics are used to perform the data quality control. Combining the cosmic shear signal with a photometric redshift distribution of a galaxy sub-sample obtained from two square degree of UBVRI-band observations of the Deep Public Survey we determine constraints for the matter density Ω_m, the mass power spectrum normalisation σ₈ and the dark energy density Ω_Λ in the magnitude interval R∈[21.5,24.5]. In this magnitude interval the effective number density of source galaxies is n=12.5arcmin^–2, and their mean redshift is z=0.78. To estimate the posterior likelihood we employ the Monte Carlo Markov Chain method. Using the aperture mass dispersion we obtain for the mass power spectrum normalisation σ₈=0.80±0.10 (1σ statistical error) at a fixed matter density Ω_m=0.30 assuming a flat universe with negligible baryon content and marginalising over the Hubble parameter and the uncertainties in the fitted redshift distribution.