Emulating the CFHTLenS Weak Lensing data: Cosmological Constraints from moments and Minkowski functionals

TL;DR

This study uses non-Gaussian features like moments and Minkowski functionals from CFHTLenS weak lensing data, employing simulations and emulators to constrain cosmological parameters with improved accuracy.

Contribution

It introduces an emulator-based approach to analyze non-Gaussian weak lensing features, providing new constraints on cosmological parameters and addressing biases in Minkowski functional analyses.

Findings

High-order moments effectively break parameter degeneracies.

Constraints on $\sigma_8$ and $\Omega_m$ are consistent with previous results.

Minkowski functionals alone show biases in parameter estimation.

Abstract

Weak gravitational lensing is a powerful cosmological probe, with non--Gaussian features potentially containing the majority of the information. We examine constraints on the parameter triplet $(\Omega_m,w,\sigma_8)$ from non-Gaussian features of the weak lensing convergence field, including a set of moments (up to $4^{\rm th}$ order) and Minkowski functionals, using publicly available data from the 154deg$^2$ CFHTLenS survey. We utilize a suite of ray--tracing N-body simulations spanning 91 points in $(\Omega_m,w,\sigma_8)$ parameter space, replicating the galaxy sky positions, redshifts and shape noise in the CFHTLenS catalogs. We then build an emulator that interpolates the simulated descriptors as a function of $(\Omega_m,w,\sigma_8)$, and use it to compute the likelihood function and parameter constraints. We employ a principal component analysis to reduce dimensionality and to help stabilize the constraints with respect to the number of bins used to construct each statistic. Using the full set of statistics, we find $\Sigma_8\equiv\sigma_8(\Omega_m/0.27)^{0.55}=0.75\pm0.04$ (68% C.L.), in agreement with previous values. We find that constraints on the $(\Omega_m,\sigma_8)$ doublet from the Minkowski functionals suffer a strong bias. However, high-order moments break the $(\Omega_m,\sigma_8)$ degeneracy and provide a tight constraint on these parameters with no apparent bias. The main contribution comes from quartic moments of derivatives.