  Spatial correlations of the observed sizes and luminosities of galaxies can
be used to estimate the magnification that arises through weak gravitational
lensing. However, the intrinsic prop- erties of galaxies can be similarly
correlated through local physical effects, and these present a possible
contamination to the weak lensing estimation. In an earlier paper (Ciarlariello
et al. 2015) we modelled the intrinsic size correlations using the halo model,
assuming the galaxy sizes reflect the mass in the associated halo. Here we
extend this work to consider galaxy magnitudes and show that these may be even
more affected by intrinsic correlations than galaxy sizes, making this a bigger
systematic for measurements of the weak lensing signal. We also quantify how
these intrinsic correlations are affected by sample selection criteria based on
sizes and magnitudes.
