Why Galaxies Care about AGB Stars. Modelling Galaxies

Understand

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.