On the Age and Metallicity Estimation of Spiral Galaxies Using Optical and Near-Infrared Photometry

Abstract

In integrated-light, some color-color diagrams that use optical and near-infrared photometry show surprisingly orthogonal grids as age and metallicity are varied, and they are coming into common usage for estimating the average age and metallicity of spiral galaxies. In this paper we reconstruct these composite grids using simple stellar population models from several different groups convolved with some plausible functional forms of star formation histories at fixed metallicity. We find that the youngest populations present (t<2 Gyr) dominate the light, and because of their presence the age-metallicity degeneracy can be partially broken with broad-band colors, unlike older populations. The scatter among simple stellar population models by different authors is, however, large at ages t<2 Gyr. The dominant uncertainties in stellar population models arise from convective core overshoot assumptions and the treatment of the thermally pulsing asymptotic giant branch phase and helium abundance may play a significant role at higher metallicities. Real spiral galaxies are unlikely to have smooth, exponential star formation histories, and burstiness will cause a partial reversion to the single-burst case, which has even larger model-to-model scatter. Finally, it is emphasized that the current composite stellar population models need some implementation of chemical enrichment histories for the proper analysis of the observational data.

33 pages, 15 figures. Accepted to ApJ (Apr 2007). The major surgery was Fig. 14

References in corpus (8)

• Evidence for TP-AGB stars in high redshift galaxies, and their effect on deriving stellar population parameters
• Calcium II Triplet Spectroscopy of LMC Red Giants. I. Abundances and Velocities for a Sample of Populous Clusters
• A Large Stellar Evolution Database for Population Synthesis Studies. III. Inclusion of the full Asymptotic Giant Branch phase and Web tools for stellar population analyses
• Physical parameters of 15 intermediate-age LMC clusters from modelling of HST colour-magnitude diagrams
• The globular cluster NGC 1978 in the Large Magellanic Cloud
• Red Giant stars in the Large Magellanic Cloud clusters
• A Database of 2MASS Near-Infrared Colors of Magellanic Cloud Star Clusters
• Integrated-light VRI imaging photometry of globular clusters in the Magellanic clouds

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