Astrophysics Seminar

Weak gravitational lensing is an important tool for probing the total matter distribution in the universe. The amplitude of matter perturbations derived from the measurement of the primary Cosmic Microwave Background (CMB) anisotropies is in disagreement with that inferred from the galaxy clustering and weak lensing survey measurements. In this context, cross-correlations between weak lensing of the CMB and weak lensing of galaxies ("cosmic shear") offer a way to obtain robust inference of cosmological parameters with reduced sensitivity to certain systematic effects. In this talk, I will review some aspects of the gravitational lensing of the CMB and galaxies. Then, I will present our measurement of and the cosmological constraints derived from the angular cross-power spectrum between the Atacama Cosmology Telescope (ACT) Data Release-4 CMB lensing and the Dark Energy Survey (DES) Year-3 cosmic shear measurement. I will also briefly discuss our current cross-correlation work with the new ACT-DR6 CMB lensing map and its expected constraining power.