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Cosmology from Cosmic Shear Power Spectra with Hyper Suprime-Cam Year 3 Data

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Thursday, May 25, 2023
2:00 pm - 3:00 pm
Roohi Dalal
Duke Cosmology Seminar

Speaker: Roohi Dalal (Princeton)
Title: Cosmology from Cosmic Shear Power Spectra with Hyper Suprime-Cam Year 3 Data

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 upto high redshifts, and the analyses serve as important preparatory studies for the next generation of weak lensing surveys. I will discuss our constraints on cosmological parameters using weak lensing cosmic shear power spectra measured from the Year 3 shear catalog of HSC. The shear catalog, prepared by Li et al. 2022, covers 416 square degrees of the northern sky, with a mean i-band seeing of 0.59 arcsec and an effective galaxy number density of 15 arcmin^-2. With an i-band magnitude limit of 24.5 mag, and four tomographic redshift bins spanning 0.3<1.5, we obtain a high-significance measurement of the cosmic shear power spectra in the multipole range 300<\ell<1800. I will describe our cosmological analysis, including the steps we take to prevent confirmation bias as well as our modeling of various sources of systematic uncertainties. I will then discuss our new constraint on the S8 parameter, and how it informs our understanding of the apparent 2-3 sigma tension between constraints on S8 from weak lensing experiments and those from the CMB. Finally, I will discuss ongoing and future work that can further shed light on the S8 tension, including an improved modeling of baryonic feedback at small scales.

Contact: Chien-Hao Lin