期刊
ASTRONOMY & ASTROPHYSICS
卷 547, 期 -, 页码 -出版社
EDP SCIENCES S A
DOI: 10.1051/0004-6361/201116983
关键词
large-scale structure of Universe; cosmological parameters; cosmology: observations; dark matter
资金
- Deutsche Forschungsgemeinschaft [Schwerpunktprogramm 1177, Transregio-SFB 33]
- European RTN DUEL
- Heidelberg Graduate School of Fundamental Physics
- US Department of Energy [DE-FG02-91ER40690]
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 Omega(m0) and sigma(8). 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.
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