Institute for Advanced Study/Princeton University Early Universe/Cosmology Lunch Discussion

The mid-2020s herald an exciting new chapter for cosmology, especially in the study of weak gravitational lensing. Stage-IV surveys—spearheaded by the Vera Rubin Observatory’s Legacy Survey of Space and Time (LSST), the Roman Space Telescope, and the Euclid Mission—will map dark matter and probe dark energy by precisely measuring cosmic shear from galaxy images. Achieving accurate weak-lensing shear estimates, which quantify how foreground large-scale structures distort background galaxies, is essential for robust cosmological constraints.
In this talk, I will review the fundamentals of weak lensing cosmology and the stringent requirements for controlling shear-estimation systematics. I will then present a newly developed framework for perturbative image processing, derived from first principles and accurate to second order in shear, that meets the LSST Dark Energy Science Collaboration (DESC) standards. Finally, I will introduce a pipeline capable of automatically deriving the perturbative shear response—capturing how observables transform under small shear distortions—for any astronomical image-processing workflow. This approach enables precise, reliable, and systematically robust shear measurements, paving the way for the next generation of weak lensing cosmology.