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Stellar Population Models Interpreting observations Colouring simulations. Claudia Maraston Institute of Cosmology and Gravitation University of Portsmouth - UK. Galaxies in real life and in the simulations Leiden - 19 September 2008. Outline.
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Stellar Population Models Interpreting observations Colouring simulations Claudia Maraston Institute of Cosmology and Gravitation University of Portsmouth - UK Galaxies in real life and in the simulations 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 Claudia MarastonLeiden 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 Claudia MarastonLeiden 19 September 2008
TP-AGB Magellanic Clouds globularclusters to test the models Maraston 2005 Claudia MarastonLeiden 19 September 2008
Onset of the Red Giant Branch Data exclude late RGB onset M05 Padova tracks Ferraro et al. 2004 Claudia MarastonLeiden 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 Claudia MarastonLeiden 19 September 2008
Age/metallicity degeneracy The same 4000 AA break!!! The near-IR is fundamental to break the degeneracies Claudia MarastonLeiden 19 September 2008
Near-IRhelps always even for starforming galaxies z~2 GOODS BzK starforming galaxies in prep. with J. Pforr E. Daddi A. Renzini A. Cimatti Claudia MarastonLeiden 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. Claudia MarastonLeiden 19 September 2008
Wake, Nichol et al. 06 Fixing the gri colors of luminous red galaxies 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 Claudia MarastonLeiden 19 September 2008
Very low level of sf excluded Claudia MarastonLeiden 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 ? Claudia MarastonLeiden 19 September 2008
