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

34 Scopus citations


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 ∼2.7σ. For DES-SV we detect B-modes at the level of 2.8σ in a non-tomographic analysis, increasing to a 5.5σB-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 languageEnglish (US)
Article numberA134
JournalAstronomy and Astrophysics
StatePublished - Apr 1 2019
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Cosmology: observations
  • Gravitational lensing: weak
  • Methods: data analysis
  • Methods: statistical
  • Surveys


Dive into the research topics of 'Consistent cosmic shear in the face of systematics: A B -mode analysis of KiDS-450, DES-SV and CFHTLenS'. Together they form a unique fingerprint.

Cite this