Dark Energy Survey Year 3 : Blue shear

UNSPECIFIED (2026) Dark Energy Survey Year 3 : Blue shear. Physical Review D, 113 (10): 103509. ISSN 2470-0010

Text (2410.22272v1)
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Abstract

Modeling the intrinsic alignment (IA) of galaxies poses a challenge to weak lensing analyses. Using the Dark Energy Survey Year 3 shape catalog, we expect less impact from IA when we limit the sample to blue, star-forming galaxies. The cosmological parameter constraints from this blue cosmic shear sample are stable to IA model choice, unlike passive galaxies in the full DES Y3 sample, the goodness-of-fit is improved and the Ωm and 8 better agree with the observations from Planck on the cosmic microwave background. Mitigating IA with sample selection in DES, rather than flexible model choices, can reduce uncertainty in 8 by a factor of 1.5.