Thesis Defense: Precision Shear Calibration for Cosmology with Current and Future Galaxy Surveys

Speaker: Sidney Mau (KIPAC) In Person and zoom

Ph.D. Candidate: Sidney Mau
Research Advisor: Pat Burchat

Zoom Link: https://stanford.zoom.us/j/96788913030
Password: Email physicsstudentservices@stanford.edu for password.

Weak lensing, amongst the most sensitive probes of dark matter and dark energy, is a premier measurement for galaxy surveys including the Dark Energy Survey (DES) and the Vera C. Rubin Observatory's Legacy Survey of Space and Time. As the statistical power of these experiments continues to improve, the requirements on the systematic uncertainties in cosmic shear measurement and calibration become ever more stringent. In this talk, I will review how shear calibration can be performed to achieve sub-percent biases. I will then present the image simulations and shear calibration for the DES six-year cosmic shear dataset, demonstrating excellent control of systematic uncertainties for more than 150,000,000 galaxies spanning 4422 square degrees of the southern sky. The simulations and calibration account for the dominant sources of shear bias, including the effects of source detection, star/galaxy confusion, object and area masking, chromatic point-spread functions, and blending between galaxies of different redshifts.

Following this, I will present further studies of the effect of chromatic point-spread functions on shear calibration including the use of image simulations to quantify the resulting systematic uncertainty and the derivation of a method to calibrate this bias for future surveys. I will conclude with evaluating how image simulations will be necessary for precision calibration of cosmic shear for weak lensing analyses with next-generation surveys.