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Forecasting the potential of weak lensing magnification to enhance LSST large-scale structure analyses

Mahony, Constance; Fortuna, Maria Cristina; Joachimi, Benjamin; Korn, Andreas; Hoekstra, Henk; Schmidt, Samuel J; (2022) Forecasting the potential of weak lensing magnification to enhance LSST large-scale structure analyses. Monthly Notices of the Royal Astronomical Society 10.1093/mnras/stac872. (In press). Green open access

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Abstract

Recent works have shown that weak lensing magnification must be included in upcoming large-scale structure analyses, such as for the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST), to avoid biasing the cosmological results. In this work we investigate whether including magnification has a positive impact on the precision of the cosmological constraints, as well as being necessary to avoid bias. We forecast this using an LSST mock catalog and a halo model to calculate the galaxy power spectra. We find that including magnification has little effect on the precision of the cosmological parameter constraints for an LSST galaxy clustering analysis, where the halo model parameters are additionally constrained by the galaxy luminosity function. In particular, we find that for the LSST gold sample (i < 25.3) including weak lensing magnification only improves the galaxy clustering constraint on Ωm by a factor of 1.03, and when using a very deep LSST mock sample (i < 26.5) by a factor of 1.3. Since magnification predominantly contributes to the clustering measurement and provides similar information to that of cosmic shear, this improvement would be reduced for a combined galaxy clustering and shear analysis. We also confirm that not modelling weak lensing magnification will catastrophically bias the cosmological results from LSST. Magnification must therefore be included in LSST large-scale structure analyses even though it does not significantly enhance the precision of the cosmological constraints.

Type: Article
Title: Forecasting the potential of weak lensing magnification to enhance LSST large-scale structure analyses
Open access status: An open access version is available from UCL Discovery
DOI: 10.1093/mnras/stac872
Publisher version: https://doi.org/10.1093/mnras/stac872
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: gravitational lensing: weak, cosmological parameters, large-scale structure of Universe, methods: analytical, methods: statistical
UCL classification: UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL
URI: https://discovery-pp.ucl.ac.uk/id/eprint/10147375
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