Why Galaxies Care about AGB Stars. Modelling Galaxies
  The Thermally-Pulsating Asymptotic Giant Branch (TP-AGB) phase of stellar
evolution has received attention only recently in galaxy evolution, but is now
an important player in our understanding of how galaxies form and evolve.
Because it is a short but very luminous phase, bright in the near-IR where dust
effects are small, the TP-AGB phase is a powerful tracer of intermediate-age
stars in galaxies up to high redshift. The spectral signature of TP-AGB stars
as defined by population synthesis models has been detected by the Spitzer
Space Telescope in high-redshift galaxies, whose spectra show an amazing
similarity to spectra of local stellar populations. Even accounting for the
high uncertainty affecting the theoretical modelling of this phase, stellar
population models including the TP-AGB have leveraged a better determination of
galaxy ages and hence stellar masses, fundamental quantities for studying
galaxy formation and evolution. They have also improved the results of
semi-analytic models, which can better reproduce colours and the K-band
luminosity function of high-z galaxies.
