1. Claudia Maraston Institute of Cosmology and Gravitation University of Portsmouth - UK Stellar Population Models Interpreting observations Colouring simulations Galaxies in real life and in the simulations Leiden - 19 September 2008

2. Claudia Maraston Leiden 19 September 2008 Outline  Stellar Population Models: basic ingredients Effect of model prescriptions on: interpreting the data ages, masses, SFR, IMF, … predicting synthetic galaxies  Effect of the considered wavelength range  Solved a mismatch between the models and the SLOAN colours of luminous red galaxies is solved

3. Claudia Maraston Leiden 19 September 2008 Stellar Population Model Adding up the energetics of stellar phases -MS -SGB -Red Giant Branch -HB -(E-AGB) -TP-AGB TP-AGB + RGB decide when the model SED turns red Maraston 2005

4. Claudia Maraston Leiden 19 September 2008 Magellanic Clouds globular clusters to test the models Maraston 2005 TP-AGB

5. Claudia Maraston Leiden 19 September 2008 Ferraro et al. 2004 Padova tracks M05 Data exclude late RGB onset Onset of the Red Giant Branch

6. Claudia Maraston Leiden 19 September 2008 Effect of stellar evolution on properties derived from data TP-AGB: lower ages/ lower stellar masses/lower dust content Maraston et al. 06, van der Wel 05.06; Wyuts et al. 07; Rodighiero et al. 07; Cimatti et al. 08; Franx et al. 08; cf. Ivo Labbe’s talk non overshooting RGB onset: same effect Maraston et al. 2006

7. Claudia Maraston Leiden 19 September 2008 Age/metallicity degeneracy The same 4000 AA break!!! The near-IR is fundamental to break the degeneracies

8. Claudia Maraston Leiden 19 September 2008 Near-IR helps always even for starforming galaxies z~2 GOODS BzK starforming galaxies in prep. with J. Pforr E. Daddi A. Renzini A. Cimatti

9. Claudia Maraston Leiden 19 September 2008 Effect of stellar pop model on semi-analytic galaxies GALICS semi-analityc model + BC/Pegase M05 Tonini, CM, Devriendt Thomas, Silk, in prep.

10. Claudia Maraston Leiden 19 September 2008 Fixing the gri colors of luminous red galaxies Wake, Nichol et al. 06 A persistent problem in matching the g,r,i colours of Luminous Red Galaxies in SLOAN over a broad z range Eisenstein et al. 2001 arbitrary offset the model up to 0.1 mag

11. Claudia Maraston Leiden 19 September 2008 Very low level of sf excluded

12. Claudia Maraston Leiden 19 September 2008 Summary Ingredients of stellar population models - TP-AGB, RGB - determine the empirical relations - ages, stellar masses, SFR - derived from data Wavelength range: including the near-IR is crucial SP models determine the spectra of synthetic galaxies from semi-analytic models or simulations Model galaxies get redder at younger ages because of the TP-AGB/RGB … Tully-Fisher relation … Colour-magnitude relation …. Luminosity functon Long-standing mismatches between models and observed SLOAN colours in the rest-frame optical have been solved To model the colour evolution of Luminous Red Galaxies in SLOAN up to z ~ 0.8 requires: empirical spectra in the model and the presence of 3% by mass of metal-poor stars --- chemical evolution or accretion ?