An enlarged cosmic shear survey with the William Herschel Telescope |
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| Authors: | Richard Massey Alexandre Refregier David J Bacon Richard Ellis Michael L Brown |
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| Institution: | Institute of Astronomy, Madingley Road, Cambridge CB3 OHA;California Institute of Technology, Pasadena, California 91125, USA;Service d'Astrophysique, CEA Saclay, F-91191 Gif sur Yvette, France;Institute for Astronomy, Blackford Hill, Edinburgh EH9 3HJ |
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| Abstract: | We report the results of a cosmic shear survey using the 4.2-m William Herschel Telescope on La Palma, to a depth of R = 25.8 ( z ≈ 0.8) , over 4 deg2. The shear correlation functions are measured on scales from 1 to 15 arcmin, and are used to constrain cosmological parameters. We ensure that our measurements are free from instrumental systematic effects by performing a series of tests, including a decomposition of the signal into E - and B -modes. We also reanalyse the data independently, using the shear measurement pipeline developed for the COMBO-17 survey. This confirms our results and also highlights various effects introduced by different implementations of the basic 'Kaiser–Squires–Broadhurst' shear measurement method. We find that the normalization of the matter power spectrum on 8 h ?1 Mpc scales is σ8= (1.02 ± 0.15)(0.3/Ω m )1/2 , where the 68 per cent confidence limit error includes noise, sample variance, covariance between angular scales, systematic effects, redshift uncertainty and marginalization over other parameters. We compare these results with other cosmic shear surveys and with recent constraints from the Wilkinson Microwave Anisotropy Probe experiment. |
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| Keywords: | gravitational lensing cosmology: observations large-scale structure of Universe |
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