Impact of spurious shear on cosmological parameter estimates from weak lensing observables
Abstract
Residual errors in shear measurements, after corrections for instrument systematics and atmospheric effects, can impact cosmological parameters derived from weak lensing observations. Here we combine convergence maps from our suite of raytracing simulations with random realizations of spurious shear. This allows us to quantify the errors and biases of the triplet (Ω_{m},w ,σ_{8}) derived from the power spectrum (PS), as well as from three different sets of nonGaussian statistics of the lensing convergence field: Minkowski functionals (MFs), loworder moments (LMs), and peak counts (PKs). Our main results are as follows: (i) We find an order of magnitude smaller biases from the PS than in previous work. (ii) The PS and LM yield biases much smaller than the morphological statistics (MF, PK). (iii) For strictly Gaussian spurious shear with integrated amplitude as low as its current estimate of σ_{sys}^{2}≈10^{7} , biases from the PS and LM would be unimportant even for a survey with the statistical power of Large Synoptic Survey Telescope. However, we find that for surveys larger than ≈100 deg^{2} , nonGaussianity in the noise (not included in our analysis) will likely be important and must be quantified to assess the biases. (iv) The morphological statistics (MF, PK) introduce important biases even for Gaussian noise, which must be corrected in large surveys. The biases are in different directions in (Ω_{m},w ,σ_{8}) parameter space, allowing selfcalibration by combining multiple statistics. Our results warrant followup studies with more extensive lensing simulations and more accurate spurious shear estimates.
 Publication:

Physical Review D
 Pub Date:
 December 2014
 DOI:
 10.1103/PhysRevD.90.123015
 arXiv:
 arXiv:1409.5130
 Bibcode:
 2014PhRvD..90l3015P
 Keywords:

 95.30.Sf;
 98.62.Sb;
 Relativity and gravitation;
 Gravitational lenses and luminous arcs;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 17 pages, 8 figures, 7 tables