Speaker
Description
We cross-correlate measurements of lensing from two sources: the Cosmic Microwave Background (CMB) from the Atacama Cosmology Telescope (ACT)’s DR6, and galaxy shear from the Dark Energy Survey (DES) Y3. This presents the highest signal-to-noise measurement of its kind to date with a value of ~17.5, marking a significant improvement from the previous value of 7.1 made using ACT-DR4. This combination is most sensitive to the amount of matter clustering in the Universe, S8 = σ8(Ωm/0.3)**0.5, providing a 4.8% measurement. CMB lensing cross-correlations with galaxy shear surveys are a powerful tool for studying structure evolution across a different redshift range to each probe individually, as well as constraining various astrophysical and systematic effects which affect each survey. Here we also constrain baryonic feedback, an important astrophysical effect that impacts the distribution of matter surrounding galaxies, through the one-parameter effective model A_mod. The galaxy systematics we calibrate include the multiplicative shear bias, photometric redshift uncertainty, and intrinsic galaxy alignments. We also develop and implement our analysis within the Simons Observatory Likelihood and Theories framework (SOLikeT), in order to prepare for future analyses both with DES-Y6 and Stage IV surveys (e.g. combining SO with Rubin/LSST).