Modelling the impact of intrinsic size and luminosity correlations on magnification estimation

TL;DR

This paper investigates how intrinsic size and luminosity correlations of galaxies can contaminate weak gravitational lensing measurements, emphasizing the importance of accounting for these effects in cosmological analyses.

Contribution

It extends previous models of intrinsic size correlations to include galaxy magnitudes, showing they may pose a larger systematic challenge for lensing studies.

Findings

Intrinsic luminosity correlations can significantly bias lensing estimates.

Sample selection criteria influence the level of intrinsic correlation contamination.

Galaxy magnitudes are more affected by intrinsic correlations than sizes.

Abstract

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.