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Age and metallicities of cluster galaxies: A1185 and coma

Rakos, Karl and Schombert, James and Odell, Andrew (2007) Age and metallicities of cluster galaxies: A1185 and coma. Astrophysical Journal, 658 (2). pp. 929-940. ISSN 1538-4357


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Publisher’s or external URL: http://dx.doi.org/10.1086/511808


We present age and metallicity determinations based on narrowband continuum colors for the galaxies in the rich clusters A1185 and Coma. Using a new technique to extract luminosity-weighted age and [Fe/H] values for non-starforming galaxies, we find that both clusters have two separate populations based on these parameters. One population is old (tau > 11 Gyr) with a distinct mass-metallicity relation. The second population is slightly younger (tau approximate to 9 Gyr) with lower metallicities and lower stellar masses. We find detectable correlations between age and galaxy mass in both populations such that older galaxies are more massive and have higher mean metallicities, confirming previous work with line indices for the same type of galaxies in other clusters (Kelson et al.; Thomas et al.). Given the previously discovered correlation between galaxy mass and alpha/Fe abundance (a measure of the duration of initial star formation; Denicolo et al.; Sanchez- Blazquez et al.), we interpret our age-metallicity correlations to imply that cluster galaxies are coeval with varying durations for their initial bursts. Our results imply shorter durations for higher mass galaxies, in contradiction to the predictions of classic galactic wind models. Since we also find a clear mass-metallicity relation for these galaxies, we conclude that star formation was more efficient for higher mass galaxies, a scenario described under the inverse wind models (Matteucci). With respect to cluster environmental effects, we find there is a significant correlation between galaxy mean age and distance from the cluster center, such that older galaxies inhabit the core.

Item Type: Article
Publisher’s Statement: © 2007 The American Astronomical Society. Published by IOP Publishing.
ID number or DOI: 10.1086/511808
Keywords: color-magnitude relation; digital sky survey; distant clusters; dwarf elliptic galaxies; fundamental-plane-survey; galaxies : elliptical and lenticular,cD; galaxies : evolution; galaxies : stellar content; globular-clusters; interacting galaxies; red-sequence; star-formation histories; stellar populations
Subjects: Q Science > QB Astronomy
NAU Depositing Author Academic Status: Faculty/Staff
Department/Unit: College of Engineering, Forestry, and Natural Science > Physics and Astronomy
Date Deposited: 30 Sep 2015 17:45
URI: http://openknowledge.nau.edu/id/eprint/421

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