Volume 547, November 2012
|Number of page(s)||5|
|Section||Cosmology (including clusters of galaxies)|
|Published online||06 November 2012|
Calibration biases in measurements of weak lensing
Zentrum für Astronomie der Universität Heidelberg,
ITA, Albert-Ueberle-Str. 2,
2 Zentrum für Astronomie der Universität Heidelberg, ARI, Mönchhofstr. 12–14, 69120 Heidelberg, Germany
3 Center for Cosmology and Astro-Particle Physics, The Ohio State University, 191 W. Woodruff Ave., Columbus, Ohio 43210, USA
4 Department of Physics, The Ohio State University, 191 W. Woodruff Ave., Columbus, Ohio 43210, USA
Accepted: 13 October 2012
As shown recently, the common KSB method for measuring weak gravitational shear creates a non-linear relation between the measured and the true ellipticity of objects. We investigate here what effect such a non-linear calibration relation may have on cosmological parameter estimates from weak lensing if a simpler, linear calibration relation is assumed. We show that the non-linear relation introduces a bias in the shear-correlation amplitude and thus a bias in the cosmological parameters Ωm0 and σ8. Its direction and magnitude depends on whether the point-spread function is narrow or wide compared to the galaxy images from which the shear is estimated. Substantial over- or underestimates of the cosmological parameters are equally possible, depending also on the variant of the KSB method. Our results show that for trustable cosmological-parameter estimates from measurements of weak lensing, one must verify that the method employed is free from ellipticity-dependent biases or monitor that the calibration relation inferred from simulations is applicable to the survey at hand.
Key words: large-scale structure of Universe / cosmological parameters / cosmology: observations / dark matter
© ESO, 2012
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.