GaBoDS: The Garching-Bonn deep survey^*,**

VII. Cosmic shear analysis

¹ Argelander-Institut für Astronomie (Founded by merging of the Sternwarte, Radioastronomisches Institut and Institut für Astrophysik und Extraterrestrische Forschung der Universität Bonn.) , Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany e-mail: mhetter@astro.uni-bonn.de
² Isaac Newton Group of Telescopes, Apartado de correos 321, 38700 Santa Cruz de La Palma, Tenerife, Spain

Received: 22 June 2006
Accepted: 6 April 2007

Abstract

Aims.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 2.2 m telescope.

Methods.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 , the mass power spectrum normalisation and the dark energy density in the magnitude interval . In this magnitude interval the effective number density of source galaxies is , and their mean redshift is . To estimate the posterior likelihood we employ the Monte Carlo Markov Chain method.

Results.Using the aperture mass dispersion we obtain for the mass power spectrum normalisation ( statistical error) at a fixed matter density assuming a flat universe with negligible baryon content and marginalising over the Hubble parameter and the uncertainties in the fitted redshift distribution.