Integrated Stellar Populations: Confronting Photometry with Spectroscopy
  We investigate the ability of spectroscopic techniques to yield realistic
star formation histories (SFHs) for the bulges of spiral galaxies based on a
comparison with their observed broadband colors. Full spectrum fitting to
optical spectra indicates that recent (within ~1 Gyr) star formation activity
can contribute significantly to the V-band flux, whilst accounting for only a
minor fraction of the stellar mass budget which is made up primarily of old
stars. Furthermore, recent implementations of stellar population (SP) models
reveal that the inclusion of a more complete treatment of the thermally
pulsating asymptotic giant branch (TP-AGB) phase to SP models greatly increases
the NIR flux for SPs of ages 0.2-2 Gyr. Comparing the optical--NIR colors
predicted from population synthesis fitting, using models which do not include
all stages of the TP-AGB phase, to the observed colors reveals that observed
optical--NIR colors are too red compared to the model predictions. However,
when a 1 Gyr SP from models including a full treatment the TP-AGB phase is
used, the observed and predicted colors are in good agreement. This has strong
implications for the interpretation of stellar populations, dust content, and
SFHs derived from colors alone.
