KiDS-1000 catalogue: Weak gravitational lensing shear measurements

¹ Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
e-mail: bengib@roe.ac.uk
² Ruhr-Universität Bochum, Astronomisches Institut, German Centre for Cosmological Lensing (GCCL), Universitätsstr. 150, 44801 Bochum, Germany
³ Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
⁴ Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
⁵ Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, NJ 08544, USA
⁶ Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK
⁷ Center for Theoretical Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warsaw, Poland
⁸ Centre for Astrophysics & Supercomputing, Swinburne University of Technology, PO Box 218, Hawthorn, VIC 3122, Australia
⁹ Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands
¹⁰ Argelander-Institut f. Astronomie, Univ. Bonn, Auf dem Huegel 71, 53121 Bonn, Germany
¹¹ INAF – Astronomical Observatory of Capodimonte, Via Moiariello 16, 80131 Napoli, Italy
¹² School of Physics and Astronomy, Sun Yat-sen University, Zhuhai Campus, Guangzhou 519082, PR China
¹³ Shanghai Astronomical Observatory (SHAO), Nandan Road 80, Shanghai 200030, PR China
¹⁴ University of Chinese Academy of Sciences, Beijing 100049, PR China

Received: 5 July 2020
Accepted: 13 October 2020

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 0.1σ change in the inferred cosmic shear constraints on the clustering cosmological parameter S₈ = σ₈ √Ω_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.