  We present a simple model for describing intrinsic correlations for galaxy
sizes based on the halo model. Studying these correlations is important both to
improve our understanding of galaxy properties and because it is an important
potential systematic for weak lensing size magnification measurements. Our
model assumes that the density field drives these intrinsic correlations and we
also model the distribution of satellite galaxies. We calculate the possible
contamination to measurements of lensing convergence power spectrum from galaxy
sizes, and show that the cross-correlation of intrinsic sizes with convergence
is potentially an important systematic. We also explore how these intrinsic
size correlations may affect surveys with different redshift depth. We find
that, in this simple approach, intrinsic size correlations cannot be neglected
in order to estimate lensing convergence power spectrum for constraining
cosmological parameters.
