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The age of cluster galaxies from continuum colors

Rakos, Karl and Schombert, James and Odell, Andrew (2008) The age of cluster galaxies from continuum colors. Astrophysical Journal, 677 (2). pp. 1019-1032. ISSN 1538-4357


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Publisher’s or external URL: http://dx.doi.org/10.1086/533513


We determine the age of 1104 early- type galaxies in eight rich clusters ( z = 0.0046 to 0.175) using a new continuum color technique. We find that galaxies in clusters divide into two populations, an old population with a mean age similar to the age of the universe ( 12 Gyr) and a younger population with a mean age of 9 Gyr. The older population follows the expected relations for mass and metallicity that imply a classic monolithic collapse origin. Although total galaxy metallicity is correlated with galaxy mass, it is uncorrelated with age. It is impossible, with the current data, to distinguish between a later epoch of star formation, longer duration of star formation, or late bursts of star formation to explain the difference between the old and young populations. However, the global properties of this younger population are correlated with cluster environmental factors, which implies secondary processes, postformation epoch, operate on the internal stellar population of a significant fraction of cluster galaxies. In addition, the mean age of the oldest galaxies in a cluster are correlated with cluster velocity dispersion, implying that galaxy formation in massive clusters begins at earlier epochs than less massive clusters.

Item Type: Article
Publisher’s Statement: © 2008 The American Astronomical Society. Published by IOP Publishing.
ID number or DOI: 10.1086/533513
Keywords: abundance ratios; cD; coma cluster; digital sky survey; elliptic galaxies; galaxies : elliptical and lenticular; galaxies : evolution; galaxies : stellar content; globular-clusters; line-strength indexes; magnitude relation; old stellar populations; photochemical evolution; spectral-energy-distributions
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/422

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