A Comparison between Semi-Analytic Model Predictions for the CANDELS
  Survey
  We compare the predictions of three independently developed semi-analytic
galaxy formation models that are being used to aid in the interpretation of
results from the CANDELS survey. These models are each applied to the same set
of halo merger trees extracted from the "Bolshoi" simulation and are carefully
tuned to match the local galaxy stellar mass function using the powerful method
of Bayesian Inference coupled with MCMC or by hand. The comparisons reveal that
in spite of the significantly different parameterizations for star formation
and feedback processes, the three models yield qualitatively similar
predictions for the assembly histories of galaxy stellar mass and star
formation over cosmic time. We show that the SAMs generally require strong
outflows to suppress star formation in low-mass halos to match the present day
stellar mass function. However, all of the models considered produce
predictions for the star formation rates and metallicities of low-mass galaxies
that are inconsistent with existing data and diverge between the models. We
suggest that large differences in the metallicity relations and small
differences in the stellar mass assembly histories of model galaxies stem from
different assumptions for the outflow mass-loading factor. Importantly, while
more accurate observational measurements for stellar mass, SFR and metallicity
of galaxies at 1<z<5 will discriminate between models, the discrepancies
between the models and existing data of these observables have already revealed
challenging problems in understanding star formation and its feedback in galaxy
formation. The three sets of models are being used to construct catalogs of
mock galaxies on light cones that have the same geometry as the CANDELS survey,
which should be particularly useful for quantifying the biases and
uncertainties on measurements and inferences from the real observations.
-ABRIDGED
