We present the first measurement of cross-correlation between the lensing potential , reconstructed from cosmic microwave background ( CMB ) polarization data , and the cosmic shear field from galaxy shapes .
This measurement is made using data from the Polarbear CMB experiment and the Subaru Hyper Suprime-Cam ( HSC ) survey .
By analyzing an 11 deg ^ { 2 } overlapping region , we reject the null hypothesis at 3.5 \sigma and constrain the amplitude of the cross-spectrum to \widehat { A } _ { lens } = 1.70 \pm 0.48 , where \widehat { A } _ { lens } is the amplitude normalized with respect to the Planck 2018 prediction , based on the flat \Lambda cold dark matter cosmology .
The first measurement of this cross-spectrum without relying on CMB temperature measurements is possible due to the deep Polarbear map with a noise level of { \sim } 6 \mathrm { \mu K } -arcmin , as well as the deep HSC data with a high galaxy number density of n _ { g } = 23 { arcmin ^ { -2 } } .
We present a detailed study of the systematics budget to show that residual systematics in our results are negligibly small , which demonstrates the future potential of this cross-correlation technique .