CFHTLenS: mapping the large-scale structure with gravitational lensing

Creators: van Waerbeke, L.; Benjamin, J.; Erben, T.; Heymans, C.; Hildebrandt, H.; Hoekstra, H.; Kitching, T. D.; Mellier, Y.; Miller, L.; Coupon, J.; Harnois-Déraps, J.; Fu, L.; Hudson, M.; Kilbinger, M.; Kuijken, K.; Rowe, B.; Schrabback, T.; Semboloni, E.; Vafaei, S.; van Uitert, E.; Velander, M.

Abstract

We present a quantitative analysis of the largest contiguous maps of projected mass density obtained from gravitational lensing shear. We use data from the 154 deg^2 covered by the Canada–France–Hawaii Telescope Lensing Survey (CFHTLenS). Our study is the first attempt to quantitatively characterize the scientific value of lensing maps, which could serve in the future as a complementary approach to the study of the dark universe with gravitational lensing. We show that mass maps contain unique cosmological information beyond that of traditional two-point statistical analysis techniques. Using a series of numerical simulations, we first show how, reproducing the CFHTLenS observing conditions, gravitational lensing inversion provides a reliable estimate of the projected matter distribution of large-scale structure. We validate our analysis by quantifying the robustness of the maps with various statistical estimators. We then apply the same process to the CFHTLenS data. We find that the two-point correlation function of the projected mass is consistent with the cosmological analysis performed on the shear correlation function discussed in the CFHTLenS companion papers. The maps also lead to a significant measurement of the third-order moment of the projected mass, which is in agreement with analytic predictions, and to a marginal detection of the fourth-order moment. Tests for residual systematics are found to be consistent with zero for the statistical estimators we used. A new approach for the comparison of the reconstructed mass map to that predicted from the galaxy distribution reveals the existence of giant voids in the dark matter maps as large as 3° on the sky. Our analysis shows that lensing mass maps are not only consistent with the results obtained by the traditional shear approach, but they also appear promising for new techniques such as peak statistics and the morphological analysis of the projected dark matter distribution.

Additional Information

© 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2013 June 3. Received 2013 April 26; in original form 2013 March 7. First published online: June 27, 2013. We would like to thank P. Schneider and B. Gillis for insightful comments on the manuscript, and Jennifer Flood for a careful editorial work on the manuscript. This work is based on observations obtained with MegaPrime/MegaCam, a joint project of the Canada– France–Hawaii Telescope (CFHT) and CEA/Irfu, at CFHT, which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers (INSU) at 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 NRC of Canada with the support of the Canadian Space Agency. We thank the CFHT staff, in particular J.-C. Cuillandre and E. Magnier, for the observations, data processing and continuous improvement of the instrument calibration. We also thank TERAPIX for quality assessment, and E. Bertin for developing some of the software used in this study. CFHTLenS data processing was made possible thanks to support from the Natural Sciences and Engineering Research Council of Canada (NSERC) and HPC specialist O. Toader. The N-body simulations were performed on the TCS supercomputer at the SciNet HPC Consortium. The early stages of the CFHTLenS project were made possible thanks to the European Commission's Marie Curie Research Training Network DUEL (MRTN-CT-2006-036133) and its support of CFHTLenS team members LF, HHi and BR. 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, Ontario Research Fund – Research Excellence and the University of Toronto. LF acknowledges support from NSFC grants 11103012 and 10878003, Innovation Program 12ZZ134 and Chen Guang project 10CG46 of SMEC, and STCSM grant 11290706600 and Pujiang Program 12PJ1406700. CH and FS acknowledge support from the European Research Council (ERC) through grant 240185. TE is supported by the DFG through project ER 327/3-1 and the Transregional Collaborative Research Centre TR 33. HHo acknowledges support from Marie Curie IRG grant 230924, the Netherlands Organisation for Scientific Research (NWO) through grant 639.042.814 and from the ERC through grant 279396. HHi is supported by the Marie Curie IOF 252760 and by a CITA National Fellowship. TDK is supported by a Royal Society University Research Fellowship. YM acknowledges support from CNRS/INSU and the Programme National Galaxies et Cosmologie (PNCG). LVW and MJH acknowledge support from NSERC. LVW also acknowledges support from the Canadian Institute for Advanced Research (CIfAR, Cosmology and Gravity programme). BR acknowledges support from the ERC through grant 24067, and the Jet Propulsion Laboratory, California Institute of Technology (NASA). TS acknowledges support from NSF through grant AST-0444059-001, SAO through grant GO0-11147A and NWO. ES acknowledges support from the NWO grant 639.042.814 and support from ERC under grant 279396. MV acknowledges support from NWO and from the Beecroft Institute for Particle Astrophysics and Cosmology. Author Contributions. All authors contributed to the development and writing of this paper. The authorship list reflects the lead author of this paper (LVW) 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 either the project, this paper or both. The CFHTLenS collaboration was co-led by CH and LVW.

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Submitted - 1303.1806v2.pdf

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