Disentangling magnification in combined shear-clustering analyses
  We investigate the sensitivity to the effects of lensing magnification on
large-scale structure analyses combining photometric cosmic shear and galaxy
clustering data (i.e. the now commonly called "3$\times$2-point" 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 Stage-III and
Stage-IV surveys, assuming well-known redshift distributions, sample selection
based on magnitude, and magnification strengths inferred from CFHTLenS and DES
Y1 data. 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 shear-clustering cross-correlations, particularly between the
highest-redshift shear bin and any lower-redshift lens sample, and that the
parameters $\Omega_{M}$, $S_8=\sigma_8\sqrt{\Omega_M/0.3}$ and $w_0$ 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$\times$2-point"
analysis.
