New Cosmology Constraints from Hyper Suprime-Cam Year 3 Data and Lessons Learned for Rubin


Roohi Dalal

The Hyper Suprime-Cam (HSC) survey is the deepest Stage III weak lensing experiment, going to ~26 mag with exquisite seeing. The depth and image quality achieved by HSC allow us to probe cosmology using weak lensing up to high redshifts, and these cosmological analyses serve as important preparatory studies for the next generation of weak lensing surveys. I will discuss our constraints on cosmological parameters from cosmic shear and 3x2pt analyses which use the Year 3 shear catalog of HSC. I will show that all four analyses give consistent constraints on S8, which describes the clumpiness of the matter distribution, and that these constraints are generally ~2 sigma lower than the constraints from CMB experiments. These analyses also give us an idea of the challenges we can expect to face with the Rubin LSST, as HSC closely resembles Rubin in terms of the depth and seeing of the survey. I will discuss the challenges faced and new systematics uncovered in the HSC analyses, including systematics from the Point Spread Function, high-redshift photo-z biases, and sensitivities to the modeling of astrophysical effects, including baryonic feedback and intrinsic alignments. Finally, I will discuss what can be learned from these analyses for the design of Rubin LSST pipelines and cosmological analyses. 


This talk will be given in the Rubin Science Medley session.


Career Stage: 
Grad Student