Strong detection of the CMB lensing and galaxy weak lensing cross-correlation from ACT-DR4, Planck Legacy, and KiDS-1000

¹ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
e-mail: ncr@ast.cam.ac.uk
² Kavli Institute for Cosmology Cambridge, Madingley Road, Cambridge CB3 0HA, UK
³ Sub-department of Astrophysics, University of Oxford, Keble Road, Oxford, OX1 3RH, UK
⁴ Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, UK
⁵ Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
⁶ Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, UK
⁷ Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, NJ 08544, USA
⁸ Kavli Institute for Particle Astrophysics & Cosmology, Stanford University, PO Box 2450, Stanford, CA 94305, USA
⁹ Center for Theoretical Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warsaw, Poland
¹⁰ School of Physics and Astronomy, Cardiff University, The Parade, Cardiff CF24 3AA, UK
¹¹ Department of Physics, Cornell University, Ithaca, NY 14853, USA
¹² Department of Astronomy, Cornell University, Ithaca, NY 14853, USA
¹³ Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104, USA
¹⁴ Joseph Henry Laboratories of Physics, Princeton University, Jadwin Hall, Princeton, NJ 08544, USA
¹⁵ Ruhr University Bochum, Faculty of Physics and Astronomy, Astronomical Institute (AIRUB), German Centre for Cosmological Lensing, 44780 Bochum, Germany
¹⁶ Argelander-Institut für Astronomie, Auf dem Hügel 71, 53121 Bonn, Germany
¹⁷ Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA
¹⁸ Berkeley Center for Cosmological Physics, UC Berkeley, CA 94720, USA
¹⁹ Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
²⁰ Physics and Astronomy Department, Stony Brook University, Stony Brook, NY 11794, USA
²¹ Department of Physics, Columbia University, New York, NY 10027, USA
²² Center for Computational Astrophysics, Flatiron Institute, New York, NY 10010, USA
²³ Astrophysics Research Centre, University of KwaZulu-Natal, Westville Campus, Durban 4041, South Africa
²⁴ School of Mathematics, Statistics & Computer Science, University of KwaZulu-Natal, Westville Campus, Durban 4041, South Africa
²⁵ Remark Department of Physics, Stanford University, Stanford, CA 94305-4085, USA
²⁶ NIST Quantum Sensors Group, 325 Broadway, Boulder, CO 80305, USA
²⁷ Department of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854-8019, USA
²⁸ Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
²⁹ Waterloo Centre for Astrophysics, University of Waterloo, 200 University Ave W, Waterloo, ON N2L 3G1, Canada
³⁰ Centre for the Universe, Perimeter Institute for Theoretical Physics, Waterloo, ON N2L 2Y5, Canada
³¹ Department of Physics, University of Milano-Bicocca, Piazza della Scienza 3, 20126 Milano, MI, Italy
³² Department of Physics and Astronomy, Haverford College, Haverford, PA 19041, USA
³³ Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA
³⁴ Instituto de Física, Pontificia Universidad Católica de Valparaíso, Casilla 4059, Valparaíso, Chile
³⁵ School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA
³⁶ Kapteyn Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands
³⁷ NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA
³⁸ MIT Kavli Institute, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA

Received: 23 November 2020
Accepted: 10 March 2021

Abstract

We measured the cross-correlation between galaxy weak lensing data from the Kilo Degree Survey (KiDS-1000, DR4) and cosmic microwave background (CMB) lensing data from the Atacama Cosmology Telescope (ACT, DR4) and the Planck Legacy survey. We used two samples of source galaxies, selected with photometric redshifts, (0.1 < z_B < 1.2) and (1.2 < z_B < 2), which produce a combined detection significance of the CMB lensing and weak galaxy lensing cross-spectrum of 7.7σ. With the lower redshift galaxy sample, for which the cross-correlation was detected at a significance of 5.3σ, we present joint cosmological constraints on the matter density parameter, Ω_m, and the matter fluctuation amplitude parameter, σ₈, marginalising over three nuisance parameters that model our uncertainty in the redshift and shear calibration as well as the intrinsic alignment of galaxies. We find our measurement to be consistent with the best-fitting flat ΛCDM cosmological models from both Planck and KiDS-1000. We demonstrate the capacity of CMB weak lensing cross-correlations to set constraints on either the redshift or shear calibration by analysing a previously unused high-redshift KiDS galaxy sample (1.2 < z_B < 2), with the cross-correlation detected at a significance of 7σ. This analysis provides an independent assessment for the accuracy of redshift measurements in a regime that is challenging to calibrate directly owing to known incompleteness in spectroscopic surveys.