KiDS-1000 catalogue: Weak gravitational lensing shear measurements

TL;DR

This paper presents a comprehensive weak lensing shear catalogue from the KiDS-1000 survey, validating its accuracy and robustness for cosmological analyses involving gravitational lensing and galaxy clustering.

Contribution

The study provides a well-calibrated shear catalogue with detailed validation, demonstrating its suitability for precise cosmological measurements and combined-probe analyses.

Findings

Shear measurements meet requirements to limit bias in cosmological parameters.

Null-tests show no significant non-lensing B-mode distortions.

Redshift scaling of galaxy-galaxy lensing signal is verified.

Abstract

We present weak lensing shear catalogues from the fourth data release of the Kilo-Degree Survey, KiDS-1000, spanning 1006 square degrees of deep and high-resolution imaging. Our `gold-sample' of galaxies, with well-calibrated photometric redshift distributions, consists of 21 million galaxies with an effective number density of $6.17$ galaxies per square arcminute. We quantify the accuracy of the spatial, temporal, and flux-dependent point-spread function (PSF) model, verifying that the model meets our requirements to induce less than a $0.1\sigma$ change in the inferred cosmic shear constraints on the clustering cosmological parameter $S_8 = \sigma_8\sqrt{\Omega_{\rm m}/0.3}$. Through a series of two-point null-tests, we validate the shear estimates, finding no evidence for significant non-lensing B-mode distortions in the data. The PSF residuals are detected in the highest-redshift bins, originating from object selection and/or weight bias. The amplitude is, however, shown to be sufficiently low and within our stringent requirements. With a shear-ratio null-test, we verify the expected redshift scaling of the galaxy-galaxy lensing signal around luminous red galaxies. We conclude that the joint KiDS-1000 shear and photometric redshift calibration is sufficiently robust for combined-probe gravitational lensing and spectroscopic clustering analyses.