Cosmological constraints from the CFHTLenS shear measurements using a new, accurate and flexible way of predicting nonlinear mass clustering

TL;DR

This paper introduces a new, accurate method for modeling nonlinear mass clustering in cosmic shear analysis, enabling precise cosmological constraints from CFHTLenS data and compatible with previous results.

Contribution

The authors develop an extension of the Angulo & White (2010) method for predicting shear correlations, improving accuracy and flexibility for cosmological parameter estimation.

Findings

Predictions are accurate within ~10% for a wide range of cosmologies.

Constraints on _8 (_0.27)^{0.6} are 0.801 b1 0.028.

Combined with CMB data, _8 = 0.81 b1 0.01 and _m = 0.29 b1 0.01.

Abstract

We explore the cosmological constraints from cosmic shear using a new way of modelling the non-linear matter correlation functions. The new formalism extends the method of Angulo & White (2010), which manipulates outputs of $N$-body simulations to represent the three-dimensional nonlinear mass distribution in different cosmological scenarios. We show that predictions from our approach for shear two-point correlations at $1$ to $300$ arcmin separations are accurate at the $\sim10$\% level, even for extreme changes in cosmology. For moderate changes, with target cosmologies similar to that preferred by analyses of recent Planck data, the accuracy is close to $\sim5$\%. We combine this approach with a MonteCarlo Markov Chain sampler to explore constraints on a $\Lambda$CDM model from the shear correlation functions measured in the Canada-France Hawaii Telescope Lensing Survey (CFHTLenS). We obtain constraints on the parameter combination $\sigma_8 (\Omega_m/0.27)^{0.6} = 0.801 \pm 0.028$. Combined with results from CMB data, we obtain marginalised constraints on $\sigma_8 = 0.81 \pm 0.01$ and $\Omega_m = 0.29 \pm 0.01$. These results are fully compatible with previous analyses, which supports the validity of our approach. We discuss the advantages of our method and the potential it offers, including a path to incorporate in detail the effects of baryons, among others effects, in future high-precision cosmological analyses.