CFHTLenS revisited: assessing concordance with Planck including astrophysical systematics

TL;DR

This study reassesses cosmic shear data from CFHTLenS in light of astrophysical systematics and compares it with Planck CMB measurements, revealing that systematic treatment influences the perceived level of dataset concordance.

Contribution

It introduces an updated CFHTLenS analysis with new simulations and a comprehensive systematic uncertainty model, evaluating their impact on cosmological constraints and dataset concordance.

Findings

Intrinsic alignment is the most favored systematic in the data.

Concordance with Planck varies from discordant to concordant depending on systematic modeling.

More conservative systematic treatments increase dataset agreement.

Abstract

We investigate the impact of astrophysical systematics on cosmic shear cosmological parameter constraints from the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS), and the concordance with cosmic microwave background measurements by Planck. We present updated CFHTLenS cosmic shear tomography measurements extended to degree scales using a covariance calibrated by a new suite of N-body simulations. We analyze these measurements with a new model fitting pipeline, accounting for key systematic uncertainties arising from intrinsic galaxy alignments, baryonic effects in the nonlinear matter power spectrum, and photometric redshift uncertainties. We examine the impact of the systematic degrees of freedom on the cosmological parameter constraints, both independently and jointly. When the systematic uncertainties are considered independently, the intrinsic alignment amplitude is the only degree of freedom that is substantially preferred by the data. When the systematic uncertainties are considered jointly, there is no consistently strong preference in favor of the more complex models. We quantify the level of concordance between the CFHTLenS and Planck datasets by employing two distinct data concordance tests, grounded in Bayesian evidence and information theory. We find that the two data concordance tests largely agree with one another, and that the level of concordance between the CFHTLenS and Planck datasets is sensitive to the exact details of the systematic uncertainties included in our analysis, ranging from decisive discordance to substantial concordance as the treatment of the systematic uncertainties becomes more conservative. The least conservative scenario is the one most favored by the cosmic shear data, but it is also the one that shows the greatest degree of discordance with Planck. The data and analysis code are public at https://github.com/sjoudaki/cfhtlens_revisited