Observed versus modelled u,g,r,i,z-band photometry of local galaxies -
  Evaluation of model performance
  We test how well available stellar population models can reproduce observed
u,g,r,i,z-band photometry of the local galaxy population (0.02<=z<=0.03) as
probed by the SDSS. Our study is conducted from the perspective of a user of
the models, who has observational data in hand and seeks to convert them into
physical quantities. Stellar population models for galaxies are created by
synthesizing star formations histories and chemical enrichments using single
stellar populations from several groups (Starburst99, GALAXEV, Maraston2005,
GALEV). The role of dust is addressed through a simplistic, but observationally
motivated, dust model that couples the amplitude of the extinction to the star
formation history, metallicity and the viewing angle. Moreover, the influence
of emission lines is considered (for the subset of models for which this
component is included). The performance of the models is investigated by: 1)
comparing their prediction with the observed galaxy population in the SDSS
using the (u-g)-(r-i) and (g-r)-(i-z) color planes, 2) comparing predicted
stellar mass and luminosity weighted ages and metallicities, specific star
formation rates, mass to light ratios and total extinctions with literature
values from studies based on spectroscopy. Strong differences between the
various models are seen, with several models occupying regions in the
color-color diagrams where no galaxies are observed. We would therefore like to
emphasize the importance of the choice of model. Using our preferred model we
find that the star formation history, metallicity and also dust content can be
constrained over a large part of the parameter space through the use of
u,g,r,i,z-band photometry. However, strong local degeneracies are present due
to overlap of models with high and low extinction in certain parts of color
space.
