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Claudia Maraston Institute of Cosmology and Gravitation University of Portsmouth, UK

Key Issues in Physical Interpretation of Galaxy spectra Discussion. Claudia Maraston Institute of Cosmology and Gravitation University of Portsmouth, UK. Carmen 2007. Issues. Models must include all major evolutionary phases Element abundance ratios

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Claudia Maraston Institute of Cosmology and Gravitation University of Portsmouth, UK

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  1. Key Issues in Physical Interpretation of Galaxy spectra Discussion Claudia Maraston Institute of Cosmology and Gravitation University of Portsmouth, UK Carmen 2007

  2. Issues • Models must include all major evolutionary phases • Element abundance ratios • Age/metallicity degeneracy: effect of hot, old stars at low redshift (GALEX) • Model uncertainties (lifetimes, temperatures, atmospheres) Hints • Predictions should be checked against star clusters • Combination of photometry and spectroscopy • Long baseline more important than a detailed but short view: it depends, for [/Fe]one just needs 2 lines • Exploit the near-IR Claudia MarastonCarmen2007

  3. Check the empirical in any case Claudia MarastonCarmen2007

  4. From the workshop Ben Panter: 1) higher metallicity for the highest redshift galaxies ---> downsizing 2) “something odd is going on”:TP-AGB Claudia MarastonCarmen2007

  5. Korn, Maraston, Thomas 2005 Caveats Defect in model atmospheres and empirical library Missing opacity of molecular lines, problems in G and later-type stars Kurucz 1979; Castelli & Kurucz 2006 Missing lines -- purely theoretical SEDs are risky Korn et al. 05; Coehlo et al. 07 Empirical libraries limited to some chemical pattern Stelib, Elodie, Miles Uncertainties in stellar evolutionary tracks Temperature of the RGB at high metallicities Maraston 2005 Overshooting/ RGB onset Ferraro et al. 2004; Maraston 2005 Rotation in massive stars G. Meynet in prep. Claudia MarastonCarmen2007

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