by Dr. Shabbir Shaikh, Arizona State University

Abstract:

Weak gravitational lensing of cosmological sources is an important probe of the total matter distribution in the Universe. Lensing of the cosmic microwave background (CMB) traces the integrated mass distribution back to the surface of last scattering, while cosmic shear from the weak lensing of galaxies traces the large-scale structure at relatively lower redshifts. Cross-correlating these two lensing signals provides a robust measurement of the amplitude of matter fluctuations, with reduced sensitivity to certain systematic effects that affect each probe individually. In this talk, I will discuss results from the cross-correlation analysis of CMB lensing maps from the Atacama Cosmology Telescope Data Release 4 (ACT DR4) and cosmic shear measurements from the Dark Energy Survey Year 3 (DES Y3). I will describe the analysis framework, highlight key aspects of the modeling, and discuss the implications of these measurements for our understanding of the late-time growth of cosmic structure. I will also comment on some aspects of the ongoing work using the ACT DR6 lensing data.