The Shear Testing Programme – I. Weak lensing analysis of simulated ground-based observations
- Creators
- Heymans, Catherine
- Massey, Richard
Abstract
The Shear Testing Programme (STEP) is a collaborative project to improve the accuracy and reliability of all weak lensing measurements in preparation for the next generation of wide-field surveys. In this first STEP paper, we present the results of a blind analysis of simulated ground-based observations of relatively simple galaxy morphologies. The most successful methods are shown to achieve percent level accuracy. From the cosmic shear pipelines that have been used to constrain cosmology, we find weak lensing shear measured to an accuracy that is within the statistical errors of current weak lensing analyses, with shear measurements accurate to better than 7 per cent. The dominant source of measurement error is shown to arise from calibration uncertainties where the measured shear is over or underestimated by a constant multiplicative factor. This is of concern as calibration errors cannot be detected through standard diagnostic tests. The measured calibration errors appear to result from stellar contamination, false object detection, the shear measurement method itself, selection bias and/or the use of biased weights. Additive systematics (false detections of shear) resulting from residual point-spread function anisotropy are, in most cases, reduced to below an equivalent shear of 0.001, an order of magnitude below cosmic shear distortions on the scales probed by current surveys. Our results provide a snapshot view of the accuracy of current ground-based weak lensing methods and a benchmark upon which we can improve. To this end we provide descriptions of each method tested and include details of the eight different implementations of the commonly used Kaiser, Squires & Broadhurst method (KSB+) to aid the improvement of future KSB+ analyses.
Additional Information
© 2006 The Authors. Journal compilation © 2006 Royal Astronomical Society. Accepted 2006 February 15. Received 2005 December 23; in original form 2005 June 6. Article first published online: 3 Apr. 2006. We thank TERAPIX (Traitement Élémentaire, Réduction et Analyse des Pixels de megacam) at the Institut d'Astrophysique de Paris for hosting the SKYMAKER simulations. We also thank the Max-Planck-Institut für Astronomie for financial and administrative support of STEP teleconferencing, and the Jet Propulsion Laboratory for financial and administrative support of the STEP workshop. CH is supported by a CITA National fellowship and acknowledges financial support from GIF. DB and MLB are supported by PPARC fellowships. SB used the UK National Cosmology Supercomputer Centre funded by PPARC, HEFCE and Silicon Graphics/Cray Research. HD is funded by a post-doctoral fellowship from the research council of Norway. TE acknowledges support from the German Science Foundation (DFG) under contract ER 327/2-1. KK acknowledges financial support provided through the European Community's Human Potential Program under contract HPRN-CT-2002- 00316, SISCO. We thank Richard Ellis for helpful discussions about the STEP project and the referee for useful comments.Attached Files
Published - HEYmnras06.pdf
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Additional details
- Eprint ID
- 23663
- Resolver ID
- CaltechAUTHORS:20110513-112544894
- Max-Planck- Institut für Astronomie
- JPL
- CITA National fellowship
- GIF
- PPARC
- Research Council of Norway
- ER 327/2-1
- German Science Foundation (DFG)
- HPRN-CT-2002- 00316, SISCO
- European Community Human Potential Program
- Created
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2011-05-17Created from EPrint's datestamp field
- Updated
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2021-11-09Created from EPrint's last_modified field