Galaxy-galaxy(-galaxy) lensing as a sensitive probe of galaxy evolution
  The gravitational lensing effect provides various ways to study the mass
environment of galaxies. We investigate how galaxy-galaxy(-galaxy) lensing can
be used to test models of galaxy formation and evolution. We consider two
semi-analytic galaxy formation models based on the Millennium Run N-body
simulation: the Durham model by Bower et al. (2006) and the Garching model by
Guo et al. (2011). We generate mock lensing observations for the two models,
and then employ Fast Fourier Transform methods to compute second- and
third-order aperture statistics in the simulated fields for various galaxy
samples. We find that both models predict qualitatively similar aperture
signals, but there are large quantitative differences. The Durham model
predicts larger amplitudes in general. In both models, red galaxies exhibit
stronger aperture signals than blue galaxies. Using these aperture measurements
and assuming a linear deterministic bias model, we measure relative bias ratios
of red and blue galaxy samples. We find that a linear deterministic bias is
insufficient to describe the relative clustering of model galaxies below ten
arcmin angular scales. Dividing galaxies into luminosity bins, the aperture
signals decrease with decreasing luminosity for brighter galaxies, but increase
again for fainter galaxies. This increase is likely an artifact due to too many
faint satellite galaxies in massive group and cluster halos predicted by the
models. Our study shows that galaxy-galaxy(-galaxy) lensing is a sensitive
probe of galaxy evolution.
