Dark Energy Survey Year 1 Results: Cross-correlation between DES Y1 galaxy weak lensing and SPT+Planck CMB weak lensing

TL;DR

This paper presents a high-significance cross-correlation measurement between galaxy weak lensing from DES Y1 data and CMB weak lensing from SPT and Planck, providing constraints on cosmological parameters and shear calibration.

Contribution

It is the first to achieve a 10.8σ detection of galaxy-CMB lensing cross-correlation using DES Y1 data and combines multiple datasets for improved cosmological constraints.

Findings

Detection significance of 10.8σ for galaxy-CMB lensing cross-correlation.

Measured correlation amplitude consistent with ΛCDM model, A ≈ 1.

Constraints on Ω_m and S_8 consistent with previous analyses.

Abstract

We cross-correlate galaxy weak lensing measurements from the Dark Energy Survey (DES) year-one (Y1) data with a cosmic microwave background (CMB) weak lensing map derived from South Pole Telescope (SPT) and Planck data, with an effective overlapping area of 1289 deg$^{2}$. With the combined measurements from four source galaxy redshift bins, we reject the hypothesis of no lensing with a significance of $10.8\sigma$. When employing angular scale cuts, this significance is reduced to $6.8\sigma$, which remains the highest signal-to-noise measurement of its kind to date. We fit the amplitude of the correlation functions while fixing the cosmological parameters to a fiducial $\Lambda$CDM model, finding $A = 0.99 \pm 0.17$. We additionally use the correlation function measurements to constrain shear calibration bias, obtaining constraints that are consistent with previous DES analyses. Finally, when performing a cosmological analysis under the $\Lambda$CDM model, we obtain the marginalized constraints of $\Omega_{\rm m}=0.261^{+0.070}_{-0.051}$ and $S_{8}\equiv \sigma_{8}\sqrt{\Omega_{\rm m}/0.3} = 0.660^{+0.085}_{-0.100}$. These measurements are used in a companion work that presents cosmological constraints from the joint analysis of two-point functions among galaxies, galaxy shears, and CMB lensing using DES, SPT and Planck data.