KiDS andEuclid: Cosmological implications of a pseudo angular power spectrum analysis of KiDS-1000 cosmic shear tomography

Abstract

We present a tomographic weak lensing analysis of the Kilo Degree Survey Data Release 4 (KiDS-1000), using a new pseudo angular power spectrum estimator (pseudo-Cℓ) under development for the ESA Euclid mission. Over 21 million galaxies with shape information are divided into five tomographic redshift bins, ranging from 0.1 to 1.2 in photometric redshift. We measured pseudo-Cℓ using eight bands in the multipole range 76 < ℓ < 1500 for auto- and cross-power spectra between the tomographic bins. A series of tests were carried out to check for systematic contamination from a variety of observational sources including stellar number density, variations in survey depth, and point spread function properties. While some marginal correlations with these systematic tracers were observed, there is no evidence of bias in the cosmological inference. B-mode power spectra are consistent with zero signal, with no significant residual contamination from E/B-mode leakage. We performed a Bayesian analysis of the pseudo-Cℓ estimates by forward modelling the effects of the mask. Assuming a spatially flat ΛCDM cosmology, we constrained the structure growth parameter S8 = σ8(Ωm/0.3)1/2 = 0.754−0.029+0.027. When combining cosmic shear from KiDS-1000 with baryon acoustic oscillation and redshift space distortion data from recent Sloan Digital Sky Survey (SDSS) measurements of luminous red galaxies, as well as the Lyman-α forest and its cross-correlation with quasars, we tightened these constraints to S8 = 0.771−0.032+0.006. These results are in very good agreement with previous KiDS-1000 and SDSS analyses and confirm a ∼3σ tension with early-Universe constraints from cosmic microwave background experiments.

Addressing Cosmological Tensions by Non-Local Gravity

“…The same 2.3σ tension also occurs with the data from DES's first year release (DESY1) [78], while the combination of KiDS-450 + VIKING + DESY1 weak lensing datasets results in a 2.5σ [79] or 3.2σ [80] tension depending on the analysis. The most recent cosmic shear data release from both KiDS-1000 and DESY3 confirms the previous estimates [18,[81][82][83][84] (S 8 = 0.759 +0.024 −0.021 from KiDS-1000 [18]). Analogous results have been obtained with the 3 × 2 pt correlation function analysis (cosmic shear correlation function, galaxy clustering angular auto-correlation function and galaxy-galaxy lensing cross-correlation function) of KiDS-1000 + BOSS + 2dFLenS datset [85].…”

Almanac: Weak Lensing power spectra and map inference on the masked sphere

“…Kilo Degree Survey (KiDS; Heymans et al 2021;Asgari et al 2021;Loureiro et al 2022), the Dark Energy Survey (DES; DES Collaboration et al 2022;Amon et al 2022;Secco et al 2022), and the Subaru Hyper Supreme-Cam survey (HSC; Mandelbaum et al 2018;Hikage et al 2019) have, together, revolutionised cosmology by using cosmic shear to challenge its standard model. Contemporary weak lensing experiments infer a growth of structure parameter (S 8 ) that is in tension with the value inferred from the cosmic microwave background (CMB) (Heymans et al 2013;MacCrann et al 2015;Lemos et al 2021;Amon & Efstathiou 2022).…”

Spurious Correlations between Galaxies and Multiepoch Image Stacks in the DESI Legacy Surveys

“…This is sometimes referred to as the transfer function of the survey; the resulting spurious correlations in the galaxy numbers can mimic cosmological imprints and bias the downstream inference. Hence, they must be mitigated, as demonstrated in recent cosmological analyses by the Dark Energy Survey (DES; see, e.g., Gatti et al 2021;Wagoner et al 2021;Rodríguez-Monroy et al 2022) and the Kilo Degree Survey (see, e.g., Johnston et al 2021;Loureiro et al 2022).…”