Fenech Conti, I.

Herbonnet, R.T.L.

Hoekstra, H.

Merten, J.

Miller, L.

Viola, M.

Monthly Notices of the Royal Astronomical Society

arXiv

We describe and test the pipeline used to measure the weak lensing shear signal from the Kilo Degree Survey (KiDS). It includes a novel method of `self-calibration' that partially corrects for the effect of noise bias. We also discuss the `weight bias' that may arise in optimally-weighted measurements, and present a scheme to mitigate that bias. To study the residual biases arising from both galaxy selection and shear measurement, and to derive an empirical correction to reduce the shear biases to $\lesssim 1\%$, we create a suite of simulated images whose properties are close to those of the KiDS survey observations. We find that the use of `self-calibration' reduces the additive and multiplicative shear biases significantly, although further correction via a calibration scheme is required, which also corrects for a dependence of the bias on galaxy properties. We find that the calibration relation itself is biased by the use of noisy, measured galaxy properties, which may limit the final accuracy that can be achieved. We assess the accuracy of the calibration in the tomographic bins used for the KiDS cosmic shear analysis, testing in particular the effect of possible variations in the uncertain distributions of galaxy size, magnitude and ellipticity, and conclude that the calibration procedure is accurate at the level of multiplicative bias $\lesssim 1\%$ required for the KiDS cosmic shear analysis

Fenech Conti, I

Herbonnet, RTL

Hoekstra, H

Merten, J

Miller, L

Viola, M

Oxford University Research Archive (ORA)

Calibration of weak-lensing shear in the Kilo-Degree Survey

I. Fenech Conti

R. Herbonnet

H. Hoekstra

J. Merten

L. Miller

M. Viola

Crossref

Fenech Conti, Ian

Herbonnet, Ricardo T.L.

Hoekstra, Henk

Merten, Julian

Miller, Lance

Viola, Massimo

Oxford University Research Archive

English

Leiden University Scholary Publications

https://ora.ox.ac.uk/objects/uuid:de06b48c-8a6a-4bf4-80a1-a75d705ab69d/files/m0852b39ac49ccfaebf8e3503d15f6891

Calibration of weak-lensing shear in the Kilo-Degree Survey

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Oxford University Research Archive (ORA)

Crossref

Oxford University Research Archive

Leiden University Scholary Publications