The source-lens clustering effect in the context of lensing tomography and its self-calibration

Y. Yu, P. Zhang, W. Lin, Weiguang Cui

    Research output: Contribution to journalArticle

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    Abstract

    © 2015. The American Astronomical Society. All rights reserved.. Cosmic shear can only be measured where there are galaxies. This source-lens clustering (SLC) effect has two sources, intrinsic source clustering and cosmic magnification (magnification/size bias). Lensing tomography can suppress the former. However, this reduction is limited by the existence of photo-z error and nonzero redshift bin width. Furthermore, SLC induced by cosmic magnification cannot be reduced by lensing tomography. Through N-body simulations, we quantify the impact of SLC on the lensing power spectrum in the context of lensing tomography. We consider both the standard estimator and the pixel-based estimator. We find that none of them can satisfactorily handle both sources of SLC. (1) For the standard estimator, SLC induced by both sources can bias the lensing power spectrum by -. Intrinsic source clustering also increases statistical uncertainties in the measured lensing power spectrum. However, the standard estimator suppresses intrinsic source clustering in the cross-spectrum. (2) In contrast, the pixel-based estimator suppresses SLC through cosmic magnification. However, it fails to suppress SLC through intrinsic source clustering and the measured lensing power spectrum can be biased low by -. In short, for typical photo-z errors (sz (1 + z) sz (1 + z)) and photo-z bin sizes (δz P = 0.2), SLC alters the lensing E-mode power spectrum by 1-10%, with and being of particular interest to weak lensing cosmology. Therefore the SLC is a severe systematic for cosmology in Stage-IV lensing surveys. We present useful scaling relations to self-calibrate the SLC effect.
    Original languageEnglish
    Pages (from-to)Article 46
    JournalAstrophysical Journal
    Volume803
    Issue number1
    DOIs
    Publication statusPublished - 2015

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    tomography
    lenses
    calibration
    cosmology
    estimators
    pixel
    power spectra
    magnification
    effect
    pixels
    simulation

    Cite this

    Yu, Y. ; Zhang, P. ; Lin, W. ; Cui, Weiguang. / The source-lens clustering effect in the context of lensing tomography and its self-calibration. In: Astrophysical Journal. 2015 ; Vol. 803, No. 1. pp. Article 46.
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    abstract = "{\circledC} 2015. The American Astronomical Society. All rights reserved.. Cosmic shear can only be measured where there are galaxies. This source-lens clustering (SLC) effect has two sources, intrinsic source clustering and cosmic magnification (magnification/size bias). Lensing tomography can suppress the former. However, this reduction is limited by the existence of photo-z error and nonzero redshift bin width. Furthermore, SLC induced by cosmic magnification cannot be reduced by lensing tomography. Through N-body simulations, we quantify the impact of SLC on the lensing power spectrum in the context of lensing tomography. We consider both the standard estimator and the pixel-based estimator. We find that none of them can satisfactorily handle both sources of SLC. (1) For the standard estimator, SLC induced by both sources can bias the lensing power spectrum by -. Intrinsic source clustering also increases statistical uncertainties in the measured lensing power spectrum. However, the standard estimator suppresses intrinsic source clustering in the cross-spectrum. (2) In contrast, the pixel-based estimator suppresses SLC through cosmic magnification. However, it fails to suppress SLC through intrinsic source clustering and the measured lensing power spectrum can be biased low by -. In short, for typical photo-z errors (sz (1 + z) sz (1 + z)) and photo-z bin sizes (δz P = 0.2), SLC alters the lensing E-mode power spectrum by 1-10{\%}, with and being of particular interest to weak lensing cosmology. Therefore the SLC is a severe systematic for cosmology in Stage-IV lensing surveys. We present useful scaling relations to self-calibrate the SLC effect.",
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    The source-lens clustering effect in the context of lensing tomography and its self-calibration. / Yu, Y.; Zhang, P.; Lin, W.; Cui, Weiguang.

    In: Astrophysical Journal, Vol. 803, No. 1, 2015, p. Article 46.

    Research output: Contribution to journalArticle

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    N2 - © 2015. The American Astronomical Society. All rights reserved.. Cosmic shear can only be measured where there are galaxies. This source-lens clustering (SLC) effect has two sources, intrinsic source clustering and cosmic magnification (magnification/size bias). Lensing tomography can suppress the former. However, this reduction is limited by the existence of photo-z error and nonzero redshift bin width. Furthermore, SLC induced by cosmic magnification cannot be reduced by lensing tomography. Through N-body simulations, we quantify the impact of SLC on the lensing power spectrum in the context of lensing tomography. We consider both the standard estimator and the pixel-based estimator. We find that none of them can satisfactorily handle both sources of SLC. (1) For the standard estimator, SLC induced by both sources can bias the lensing power spectrum by -. Intrinsic source clustering also increases statistical uncertainties in the measured lensing power spectrum. However, the standard estimator suppresses intrinsic source clustering in the cross-spectrum. (2) In contrast, the pixel-based estimator suppresses SLC through cosmic magnification. However, it fails to suppress SLC through intrinsic source clustering and the measured lensing power spectrum can be biased low by -. In short, for typical photo-z errors (sz (1 + z) sz (1 + z)) and photo-z bin sizes (δz P = 0.2), SLC alters the lensing E-mode power spectrum by 1-10%, with and being of particular interest to weak lensing cosmology. Therefore the SLC is a severe systematic for cosmology in Stage-IV lensing surveys. We present useful scaling relations to self-calibrate the SLC effect.

    AB - © 2015. The American Astronomical Society. All rights reserved.. Cosmic shear can only be measured where there are galaxies. This source-lens clustering (SLC) effect has two sources, intrinsic source clustering and cosmic magnification (magnification/size bias). Lensing tomography can suppress the former. However, this reduction is limited by the existence of photo-z error and nonzero redshift bin width. Furthermore, SLC induced by cosmic magnification cannot be reduced by lensing tomography. Through N-body simulations, we quantify the impact of SLC on the lensing power spectrum in the context of lensing tomography. We consider both the standard estimator and the pixel-based estimator. We find that none of them can satisfactorily handle both sources of SLC. (1) For the standard estimator, SLC induced by both sources can bias the lensing power spectrum by -. Intrinsic source clustering also increases statistical uncertainties in the measured lensing power spectrum. However, the standard estimator suppresses intrinsic source clustering in the cross-spectrum. (2) In contrast, the pixel-based estimator suppresses SLC through cosmic magnification. However, it fails to suppress SLC through intrinsic source clustering and the measured lensing power spectrum can be biased low by -. In short, for typical photo-z errors (sz (1 + z) sz (1 + z)) and photo-z bin sizes (δz P = 0.2), SLC alters the lensing E-mode power spectrum by 1-10%, with and being of particular interest to weak lensing cosmology. Therefore the SLC is a severe systematic for cosmology in Stage-IV lensing surveys. We present useful scaling relations to self-calibrate the SLC effect.

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