Open AccessCosmic variance of weak lensing surveys in the non‐Gaussian regime
Author(s) -
Semboloni Elisabetta,
Van Waerbeke Ludovic,
Heymans Catherine,
Hamana Takashi,
Colombi Stephane,
White Martin,
Mellier Yannick
Publication year - 2007
Publication title -
monthly notices of the royal astronomical society: letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.067
H-Index - 122
eISSN - 1745-3933
pISSN - 1745-3925
DOI - 10.1111/j.1745-3933.2006.00266.x
Subject(s) - cosmic variance , weak gravitational lensing , gaussian , physics , redshift , cosmology , gaussian random field , cosmic cancer database , statistics , variance (accounting) , astrophysics , statistical physics , gaussian function , mathematics , galaxy , quantum mechanics , accounting , business
The results from weak gravitational lensing analyses are subject to a cosmic variance error term that has previously been estimated assuming Gaussian statistics. In this Letter we address the issue of estimating cosmic variance errors for weak lensing surveys in the non‐Gaussian regime. Using standard cold dark matter model ray‐tracing simulations characterized by Ω m = 0.3, Ω Λ = 0.7, h = 0.7 and σ 8 = 1 for different survey redshifts z s , we determine the variance of the two‐point shear correlation function measured across 64 independent lines of sight. We compare the measured variance to the variance expected from a random Gaussian field and derive a redshift‐dependent non‐Gaussian calibration relation. We find that the ratio between the non‐Gaussian and Gaussian variance at 1 arcmin can be as high as ∼30 for a survey with source redshift z s ∼ 0.5 and ∼10 for z s ∼ 1 . The transition scale ϑ c above which the ratio is consistent with unity is found to be ϑ c ∼ 20 arcmin for z s ∼ 0.5 and ϑ c ∼ 10 arcmin for z s ∼ 1 . We provide fitting formulae to our results permitting the estimation of non‐Gaussian cosmic variance errors, and discuss the impact on current and future surveys. A more extensive set of simulations will, however, be required to investigate the dependence of our results on cosmology, specifically on the amplitude of clustering.