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Claudia Maraston
Institute of Cosmology and GravitationUniversity of Portsmouth - UK
Stellar Population ModelsInterpreting observations
Colouring simulations
Galaxies in real life and in the simulations Leiden - 19 September 2008
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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
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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
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Claudia Maraston Leiden 19 September 2008
Magellanic Clouds globularclusters to test
the models
Maraston 2005
TP-AGB
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Claudia Maraston Leiden 19 September 2008Ferraro et al. 2004
Padova tracks
M05
Data exclude late RGB onset
Onset of the Red Giant Branch
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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
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Claudia Maraston Leiden 19 September 2008
Age/metallicity degeneracy
The same 4000 AA break!!! The near-IR is fundamentalto break the degeneracies
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Claudia Maraston Leiden 19 September 2008
Near-IR helps always even for starforming galaxies
z~2 GOODSBzK starforminggalaxies
in prep. withJ. PforrE. DaddiA. RenziniA. Cimatti
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Claudia Maraston Leiden 19 September 2008
Effect of stellar pop model on semi-analytic galaxiesGALICS
semi-analitycmodel +
BC/Pegase
M05
Tonini,CM,DevriendtThomas,Silk,in prep.
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Claudia Maraston Leiden 19 September 2008
Fixing the gri colors of luminous red galaxies
Wake, Nichol et al. 06
A persistent problem in matchingthe g,r,i colours of LuminousRed Galaxies in SLOAN over a broad z range
Eisenstein et al. 2001 arbitrary offsetthe model up to 0.1 mag
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Claudia Maraston Leiden 19 September 2008
Very low level of sf excluded
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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 ?