Disentangling magnification in combined shearclustering analyses
Abstract
ABSTRACT We investigate the sensitivity to the effects of lensing magnification on largescale structure analyses combining photometric cosmic shear and galaxy clustering data (i.e. the now commonly called ‘3 × 2point’ analysis). Using a Fisher matrix bias formalism, we disentangle the contribution to the bias on cosmological parameters caused by ignoring the effects of magnification in a theory fit from individual elements in the data vector, for StageIII and StageIV surveys. We show that the removal of elements of the data vectors that are dominated by magnification does not guarantee a reduction in the cosmological bias due to the magnification signal, but can instead increase the sensitivity to magnification. We find that the most sensitive elements of the data vector come from the shearclustering crosscorrelations, particularly between the highest redshift shear bin and any lower redshift lens sample, and that the parameters ΩM, $$S_8=\sigma _8\sqrt{\Omega _\mathrm{ M}/0.3}$$, and w0 show the most significant biases for both survey models. Our forecasts predict that current analyses are not significantly biased by magnification, but this bias will become highly significant with the continued increase of statistical power in the near future. We therefore conclude that future surveys should measure and model the magnification as part of their flagship ‘3 × 2point’ analysis.
 Authors:

 Astrophysics, Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK, Perimeter Institute, 31 Caroline Street North, Waterloo, ON N2L 2Y5, Canada, Department of Physics and Astronomy, University of Waterloo, Waterloo, ON N2L 3G1, Canada
 Astrophysics, Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK
 Publication Date:
 Sponsoring Org.:
 USDOE
 OSTI Identifier:
 1576662
 Resource Type:
 Published Article
 Journal Name:
 Monthly Notices of the Royal Astronomical Society
 Additional Journal Information:
 Journal Name: Monthly Notices of the Royal Astronomical Society Journal Volume: 491 Journal Issue: 2; Journal ID: ISSN 00358711
 Publisher:
 Oxford University Press
 Country of Publication:
 United Kingdom
 Language:
 English
Citation Formats
Thiele, Leander, Duncan, Christopher A. J., and Alonso, David. Disentangling magnification in combined shearclustering analyses. United Kingdom: N. p., 2019.
Web. doi:10.1093/mnras/stz3103.
Thiele, Leander, Duncan, Christopher A. J., & Alonso, David. Disentangling magnification in combined shearclustering analyses. United Kingdom. doi:10.1093/mnras/stz3103.
Thiele, Leander, Duncan, Christopher A. J., and Alonso, David. Tue .
"Disentangling magnification in combined shearclustering analyses". United Kingdom. doi:10.1093/mnras/stz3103.
@article{osti_1576662,
title = {Disentangling magnification in combined shearclustering analyses},
author = {Thiele, Leander and Duncan, Christopher A. J. and Alonso, David},
abstractNote = {ABSTRACT We investigate the sensitivity to the effects of lensing magnification on largescale structure analyses combining photometric cosmic shear and galaxy clustering data (i.e. the now commonly called ‘3 × 2point’ analysis). Using a Fisher matrix bias formalism, we disentangle the contribution to the bias on cosmological parameters caused by ignoring the effects of magnification in a theory fit from individual elements in the data vector, for StageIII and StageIV surveys. We show that the removal of elements of the data vectors that are dominated by magnification does not guarantee a reduction in the cosmological bias due to the magnification signal, but can instead increase the sensitivity to magnification. We find that the most sensitive elements of the data vector come from the shearclustering crosscorrelations, particularly between the highest redshift shear bin and any lower redshift lens sample, and that the parameters ΩM, $S_8=\sigma _8\sqrt{\Omega _\mathrm{ M}/0.3}$, and w0 show the most significant biases for both survey models. Our forecasts predict that current analyses are not significantly biased by magnification, but this bias will become highly significant with the continued increase of statistical power in the near future. We therefore conclude that future surveys should measure and model the magnification as part of their flagship ‘3 × 2point’ analysis.},
doi = {10.1093/mnras/stz3103},
journal = {Monthly Notices of the Royal Astronomical Society},
number = 2,
volume = 491,
place = {United Kingdom},
year = {2019},
month = {11}
}
DOI: 10.1093/mnras/stz3103
Web of Science
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