CFHTLenS: the Canada–France–Hawaii Telescope Lensing Survey

Creators: Heymans, Catherine; Van Waerbeke, Ludovic; Miller, Lance; Erben, Thomas; Hildebrandt, Hendrik; Hoekstra, Henk; Kitching, Thomas D.; Mellier, Yannick; Simon, Patrick; Bonnett, Christopher; Coupon, Jean; Fu, Liping; Harnois-Déraps, Joachim; Hudson, Michael J.; Kilbinger, Martin; Kuijken, Koenraad; Rowe, Barnaby; Schrabback, Tim; Semboloni, Elisabetta; van Uitert, Edo; Vafaei, Sanaz; Velander, Malin

Abstract

We present the Canada–France–Hawaii Telescope Lensing Survey (CFHTLenS) that accurately determines a weak gravitational lensing signal from the full 154 deg^2 of deep multicolour data obtained by the CFHT Legacy Survey. Weak gravitational lensing by large-scale structure is widely recognized as one of the most powerful but technically challenging probes of cosmology. We outline the CFHTLenS analysis pipeline, describing how and why every step of the chain from the raw pixel data to the lensing shear and photometric redshift measurement has been revised and improved compared to previous analyses of a subset of the same data. We present a novel method to identify data which contributes a non-negligible contamination to our sample and quantify the required level of calibration for the survey. Through a series of cosmology-insensitive tests we demonstrate the robustness of the resulting cosmic shear signal, presenting a science-ready shear and photometric redshift catalogue for future exploitation.

Additional Information

© 2012 The Authors. Monthly Notices of the Royal Astronomical Society. © 2012 RAS. Accepted 2012 August 15. Received 2012 August 13; in original form 2012 July 19. Article first published online: 29 Oct. 2012. We would particularly like to thank the dedication of the CFHTLenS manual masking team that included some of the co-authors in addition to Jonathan Benjamin, Raphael Gavazzi, Bryan Gillis, Emma Grocutt, Karianne Holhjem, Martha Milkeraitis and Merijn Smit. We would also like to thank the anonymous referee for prompt helpful comments and thorough reading of the manuscript, in addition to Alan Heavens, Gary Bernstein, Mike Jarvis, Sarah Bridle and Robert Lupton for their many constructive ideas during the development of this project. This work is based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the CFHT which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This research used the facilities of the Canadian Astronomy Data Centre operated by the National Research Council of Canada with the support of the Canadian Space Agency. We thank the CFHT staff for successfully conducting the CFHTLS observations and in particular Jean-Charles Cuillandre and Eugene Magnier for the continuous improvement of the instrument calibration and the ELIXIR detrended data that we used. We also thank TERAPIX for the quality assessment and validation of individual exposures during the CFHTLS data acquisition period, and Emmanuel Bertin for developing some of the software used in this study. CFHTLenS data processing was made possible thanks to significant computing support from the NSERC Research Tools and Instruments grant programme, and to HPC specialist Ovidiu Toader. The N-body simulations used in this analysis were performed on the TCS supercomputer at the SciNet HPC Consortium. SciNet is funded by: the Canada Foundation for Innovation under the auspices of Compute Canada; the Government of Ontario; the Ontario Research Fund – Research Excellence; and the University of Toronto. The early stages of the CFHTLenS project were made possible thanks to the support of the European Commissions Marie Curie Research Training Network DUEL (MRTN-CT-2006-036133) which directly supported six members of the CFHTLenS team (LF, HHi, PS, BR, CB, MV) between 2007 and 2011 in addition to providing travel support and expenses for team meetings. CH, HHo and BR acknowledge support from the European Research Council under the EC FP7 grant numbers 240185 (CH), 279396 (HHo) and 240672 (BR). LVW acknowledges support from the Natural Sciences and Engineering Research Council of Canada and the Canadian Institute for Advanced Research (Cosmology and Gravity programme). TE is supported by the Deutsche Forschungsgemeinschaft through project ER 327/3-1 and, with PS, is supported by the Transregional Collaborative Research Centre TR 33 – 'The Dark Universe'. HHi is supported by the Marie Curie IOF 252760 and by a CITA National Fellowship. HHo also acknowledges support from Marie Curie IRG grant 230924 and the Netherlands Organisation for Scientific Research grant number 639.042.814. TDK acknowledges support from a Royal Society University Research Fellowship. YM acknowledges support from CNRS/INSU (Institut National des Sciences de l'Univers) and the Programme National Galaxies et Cosmologie (PNCG). LF acknowledges support from NSFC grants 11103012 and 10878003, Innovation Program 12ZZ134 and Chen Guang project 10CG46 of SMEC, and STCSM grant 11290706600. MJH acknowledges support from the Natural Sciences and Engineering Research Council of Canada. TS acknowledges support from NSF through grant AST-0444059-001, SAO through grant GO0-11147A, and NWO. MV acknowledges support from the Netherlands Organisation for Scientific Research (NWO) and from the Beecroft Institute for Particle Astrophysics and Cosmology. CB is supported by the Spanish Science Ministry AYA2009-13936 Consolider-Ingenio CSD2007-00060, project 2009SGR1398 from Generalitat de Catalunya and by the European Commissions Marie Curie Initial Training Network CosmoComp (PITN-GA-2009-238356). Part of BR's work was done at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Author Contributions: All authors contributed to the development and writing of this paper. CH and LVW co-led the CFHTLenS collaboration. The authorship list reflects the lead authors of this paper (CH, LVW and LM) followed by two alphabetical groups. The first alphabetical group includes key contributors to the science analysis and interpretation in this paper, the founding core team and those whose long-term significant effort produced the final CFHTLenS data product. The second group covers members of the CFHTLenS team who made a significant contribution to the project and/or this paper.

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