STATISTICAL AND SYSTEMATIC ERRORS IN THE MEASUREMENT OF WEAK-LENSING MINKOWSKI FUNCTIONALS: APPLICATION TO THE CANADA-FRANCE-HAWAII LENSING SURVEY

Abstract

The measurement of cosmic shear using weak gravitational lensing is a\nchallenging task that involves a number of complicated procedures. We study in\ndetail the systematic errors in the measurement of weak lensing Minkowski\nFunctionals (MFs). Specifically, we focus on systematics associated with galaxy\nshape measurements, photometric redshift errors, and shear calibration\ncorrection. We first generate mock weak-lensing catalogs that directly\nincorporate the actual observational characteristics of the\nCanada-France-Hawaii Lensing Survey (CFHTLenS). We then perform a Fisher\nanalysis using the large set of mock catalogs for various cosmological models.\nWe find that the statistical error associated with the observational effects\ndegrades the cosmological parameter constraints by a factor of a few. The\nSubaru Hyper Suprime-Cam (HSC) survey with a sky coverage of ~1400 deg2 will\nconstrain the dark energy equation of the state parameter with an error of\nDelta w_0 ~ 0.25 by the lensing MFs alone, but biases induced by the\nsystematics can be comparable to the 1-sigma error. We conclude that the\nlensing MFs are powerful statistics beyond the two-point statistics, only if\nwell-calibrated measurement of both the redshifts and the shapes of source\ngalaxies is performed. Finally, we analyze the CFHTLenS data to explore the\nability of the MFs to break degeneracies between a few cosmological parameters.\nUsing a combined analysis of the MFs and the shear correlation function, we\nderive the matter density Omega_m0= 0.256+0.054-0.046.\n