# Consistent cosmic shear in the face of systematics: a B-mode analysis of KiDS-450, DES-SV and CFHTLenS

Marika Asgari, Catherine Heymans, Hendrik Hildebrandt, Lance Miller, Peter Schneider, Alexandra Amon, Ami Choi, Thomas Erben, Christos Georgiou, Joachim Harnois-Deraps, Konrad Kuijken

Research output: Contribution to journalArticlepeer-review

## Abstract

We analyse three public cosmic shear surveys; the Kilo-Degree Survey (KiDS-450), the Dark Energy Survey (DES-SV) and the Canada France Hawaii Telescope Lensing Survey (CFHTLenS). Adopting the COSEBIs statistic to cleanly and completely separate the lensing E-modes from the non-lensing B-modes, we detect B-modes in KiDS-450 and CFHTLenS at the level of about 2.7 $\sigma$. For DES- SV we detect B-modes at the level of 2.8 $\sigma$ in a non-tomographic analysis, increasing to a 5.5 $\sigma$ B-mode detection in a tomographic analysis. In order to understand the origin of these detected B-modes we measure the B-mode signature of a range of different simulated systematics including PSF leakage, random but correlated PSF modelling errors, camera-based additive shear bias and photometric redshift selection bias. We show that any correlation between photometric-noise and the relative orientation of the galaxy to the point-spread-function leads to an ellipticity selection bias in tomographic analyses. This work therefore introduces a new systematic for future lensing surveys to consider. We find that the B-modes in DES-SV appear similar to a superposition of the B-mode signatures from all of the systematics simulated. The KiDS-450 and CFHTLenS B-mode measurements show features that are consistent with a repeating additive shear bias.
Original language English A134 1-33 33 Astronomy & Astrophysics 624 25 Apr 2019 https://doi.org/10.1051/0004-6361/201834379 E-pub ahead of print - 25 Apr 2019

• astro-ph.CO

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• ### GLOBE: Global Lensing Observations to go Beyond Einstein (027451/1)

Heymans, C.

EU government bodies

1/11/1531/10/21

Project: Research