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  • 标题:Magnification bias in the shear-ratio test: a viable mitigation strategy
  • 本地全文:下载
  • 作者:Sandra Unruh ; Peter Schneider ; Stefan Hilbert
  • 期刊名称:Astronomy & Astrophysics
  • 印刷版ISSN:0004-6361
  • 电子版ISSN:1432-0746
  • 出版年度:2019
  • 卷号:623
  • DOI:10.1051/0004-6361/201834151
  • 语种:English
  • 出版社:EDP Sciences
  • 摘要:Using the same lens galaxies, the ratios of tangential shears for different source galaxy redshifts is equal to the ratios of their corresponding angular-diameter distances. This is the so-called shear-ratio test (SRT) and it is valid when effects induced by the intervening large-scale structure (LSS) can be neglected. The dominant LSS effect is magnification bias which, on the one hand, induces an additional shear, and on the other hand, causes a magnification of the lens population. Our objective is to quantify the magnification bias for the SRT and show an easy-to-apply mitigation strategy that does not rely on additional observations. We use ray-tracing data through the Millennium simulation to measure the influence of magnification on the SRT and test our mitigation strategy. Using the SRT as a null-test we find deviations from zero up to 10% for a flux-limited sample of lens galaxies, which is a strong function of lens redshift and the lens-source line-of-sight separation. Using our mitigation strategy we can improve the null-test by a factor of ∼100.
  • 关键词:engravitational lensing: weakmethods: statistical
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