Cosmic shear calibration with forward modeling

Claudio Bruderer, Andrina Nicola, Adam Amara, Alexandre Refregier, Jörg Herbel, Tomasz Kacprzak

Research output: Contribution to journalArticlepeer-review


Weak Gravitational Lensing is a powerful probe of the dark sector of the Universe. One of the main challenges for this technique is the treatment of systematics in the measurement of cosmic shear from galaxy shapes. In an earlier work, [1] have proposed the Monte Carlo Control Loops (MCCL) to overcome these effects using a forward modeling approach. We focus here on one of the control loops in this method, the task of which is the calibration of the shear measurement. For this purpose, we first consider the requirements on the shear systematics for a given survey and propagate them to different systematics terms. We use two one-point statistics to calibrate the shear measurement and six further one-point statistics as diagnostics. We also propagate the systematics levels that we estimate from the one-point functions to the two-point functions for the different systematic error sources. This allows us to assess the consistency between the systematics levels measured in different ways. To test the method, we construct synthetic sky surveys with an area of 1,700°2. With some simplifying assumptions, we are able to meet the requirements on the shear calibration for this survey configuration. Furthermore, we account for the total residual shear systematics in terms of the contributing sources. We discuss how this framework can be applied within analyses of current and future weak lensing surveys.

Original languageEnglish
Article number007
JournalJournal of Cosmology and Astroparticle Physics
Issue number8
Publication statusPublished - 8 Aug 2018


  • galaxy surveys
  • weak gravitational lensing


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