Forecasting the potential of weak lensing magnification to enhance LSST
  large-scale structure analyses
  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 $\Omega_{\rm{m}}$ 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.
