Modelling galaxy clustering: Is new physics needed in galaxy formation
  models?
  The clustering amplitude of galaxies depends on their intrinsic luminosity.
We compare the properties of publicly available galaxy formation models with
clustering measurements from the two-degree field galaxy redshift survey. The
model predictions show the same qualitative behaviour as the data but fail to
match the observations at the level of accuracy at which current measurements
can be made. We demonstrate that this is due to the model producing too many
satellite galaxies in massive haloes. We implement simple models to describe
two new processes, satellite-satellite mergers and the tidal dissolution of
satellites to investigate their impact on the predicted clustering. We find
that both processes need to be included in order to produce a model which
matches the observations.
