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

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 < zB < 1.2) and (1.2 < zB < 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, Ωm, 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 < zB < 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.

Joint analysis of DES Year 3 data and CMB lensing from SPT and Planck II: Cross-correlation measurements and cosmological constraints

“…Similar analyses have recently been carried out using different galaxy imaging surveys and CMB data. [19] studied the cross-correlation of the galaxy weak lensing from the Hyper Suprime-Cam Subaru Strategic Program Survey [HSC-SSP, 20] and the Planck lensing map [21]; [22] used the same HSC galaxy weak lensing measurement to cross-correlate with CMB lensing from the PO-LARBEAR experiment [23]; [24] cross-correlated galaxy weak lensing from the Kilo-Degree Survey [KiDS,25] and the CMB lensing map from the Atacama Cosmology Telescope [ACT,26]; and [27] cross-correlated the galaxy density measured in unWISE data [28] with Planck CMB lensing. Compared to these previous studies, in addition to the new datasets, this paper is unique in that we combine δ g κ CMB and γ t κ CMB .…”

Cosmology from weak lensing alone and implications for the Hubble tension

“…For Gaussian fields the neglected cross-covariance is proportional to the square of the cross-correlation between the two signals. Although this is non-zero (see Hall & Taylor 2014 for its modelling and Harnois-Déraps et al 2017;Robertson et al 2021 for its measurement in KiDS), it is small compared with the diagonal terms of the covariance at each Fourier mode, which justifies treating these the two data vectors as independent.…”

Joint analysis of DES Year 3 data and CMB lensing from SPT and Planck I: Construction of CMB Lensing Maps and Modeling Choices

“…Cross-correlations of galaxy surveys with CMB lensing can exploit this sensitivity to achieve tighter constraints on the high-redshift Universe than with galaxy surveys alone [e.g. [4][5][6][7][8][9][10][11]. CMB lensing also offers a probe of LSS that shares (almost) no sources of systematic error with measurements from galaxy surveys.…”