1808.07335
A unified analysis of four cosmic shear surveys
Chang, Wang, Dodelson, Eifler, Heymans, Jarvis, Jee, Joudaki, Krause, Malz, Mandelbaum, Mohammed, Schneider, Timet, Troxel, Zuntz
In the past few years, several independent collaborations have presented cosmological constraints from tomographic cosmic shear analyses. These analyses differ in many aspects: the datasets, the shear and photometric redshift estimation algorithms, the theory model assumptions, and they inference pipelines. To assess the robustness of the existing cosmic shear results, present in this paper a united analysis of four of the recent cosmic shear surveys: DLS, CFHTLenS, DES-SV, and KiDS-450. By using a unified pipeline, show how the cosmological constraints are sensitive to the various details of the pipeline. Identify several analysis choices that can shift the cosmological constraints by a significant fraction of the uncertainties. For the fiducial analysis choice, considering a Gaussian covariance, conservative scale cuts, assuming no baryonic feedback contamination, identical cosmological parameter priors and IA treatments, find the constraints (mean, 16% and 84% confidence intervals) on the parameter S_8==sigma_8 (Omega_m/0.3)^0.5 to be S_8=0.94_-0.045^+0.046 (DLS), 0.66-0.071+0.070 (CHFTLenS), 0.84-0.061+0.062 (DES-SV) and 0.76-0.049+0.048 (KiDS-450). From the goodness-of-fit and the Bayesian evidence ratio, determine that amongst the 4 surveys, the 2 more recent surveys, DES-SV and KiDS-450, have acceptable goodness-of-fit an are consistent with each other. The combined constraints are S_8=0.79+0.042-0.041, which is in good agreement with the first year of DES cosmic shear results and recent CMB constraints from the Planck satellite.
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