Tidal Disruption of Satellite Galaxies in a Semi-Analytic Model of
  Galaxy Formation
  We introduce a new physical recipe into the De Lucia and Blaizot version of
the Munich semi-analytic model built upon the Millennium dark matter
simulation: the tidal stripping of stellar material from satellite galaxies
during mergers. To test the significance of the new physical process we apply a
Monte Carlo Markov Chain parameter estimation technique constraining the model
with the $K$-band luminosity function, $B-V$ colours and the black hole-bulge
mass relation. The differences in parameter correlations, and in the allowed
regions in likelihood space, reveal the impact of the new physics on the basic
ingredients of the model, such as the star-formation laws, feedback recipes and
the black hole growth model. With satellite disruption in place, we get a model
likelihood four times higher than in the original model, indicating that the
new process seems to be favoured by observations. This is achieved mainly due
to a reduction in black hole growth that produces a better agreement between
the properties of central black holes and host galaxies. Compared to the
best-fit model without disruption, the new model removes the excess of dwarf
galaxies in the original recipe with a more modest supernova heating. The new
model is now consistent with the three observational data sets used to
constrain it, while significantly improving the agreement with observations for
the distribution of metals in stars. Moreover, the model now follows the build
up of intra-cluster light.
