KiDS+VIKING-450 and DES-Y1 combined: Mitigating baryon feedback uncertainty with COSEBIs
Marika Asgari, Tilman Tröster, Catherine Heymans, H. Hildebrandt, Jan Luca van den Busch, Angus H. Wright, Ami Choi, T. Erben, Benjamin Joachimi, Shahab Joudaki, Arun Kannawadi, Konrad Kuijken, Chieh-An Lin, Peter Schneider, J. Zuntz
Abstract
We present cosmological constraints from a joint cosmic shear analysis of the Kilo-Degree Survey (KV450) and the Dark Energy Survey (DES-Y1), which were conducted using Complete Orthogonal Sets of E / B -Integrals (COSEBIs). With COSEBIs, we isolated any B -modes that have a non-cosmic shear origin and demonstrate the robustness of our cosmological E -mode analysis as no significant B -modes were detected. We highlight how COSEBIs are fairly insensitive to the amplitude of the non-linear matter power spectrum at high k -scales, mitigating the uncertain impact of baryon feedback in our analysis. COSEBIs, therefore, allowed us to utilise additional small-scale information, improving the DES-Y1 joint constraints on S 8 = σ 8 (Ω m /0.3) 0.5 and Ω m by 20%. By adopting a flat ΛCDM model we find S 8 = 0.755 −0.021 +0.019 , which is in 3.2 σ tension with the Planck Legacy analysis of the cosmic microwave background.