Cosmic CARNage I: on the calibration of galaxy formation models
  We present a comparison of nine galaxy formation models, eight
semi-analytical and one halo occupation distribution model, run on the same
underlying cold dark matter simulation (cosmological box of co-moving width
125$h^{-1}$ Mpc, with a dark-matter particle mass of $1.24\times 10^9 h^{-1}$
Msun) and the same merger trees. While their free parameters have been
calibrated to the same observational data sets using two approaches, they
nevertheless retain some 'memory' of any previous calibration that served as
the starting point (especially for the manually-tuned models). For the first
calibration, models reproduce the observed z = 0 galaxy stellar mass function
(SMF) within 3-{\sigma}. The second calibration extended the observational data
to include the z = 2 SMF alongside the z~0 star formation rate function, cold
gas mass and the black hole-bulge mass relation. Encapsulating the observed
evolution of the SMF from z = 2 to z = 0 is found to be very hard within the
context of the physics currently included in the models. We finally use our
calibrated models to study the evolution of the stellar-to-halo mass (SHM)
ratio. For all models we find that the peak value of the SHM relation decreases
with redshift. However, the trends seen for the evolution of the peak position
as well as the mean scatter in the SHM relation are rather weak and strongly
model dependent. Both the calibration data sets and model results are publicly
available.
