Age, Metallicity and Star Formation History of Cluster Galaxies at z~0.3 F

Abstract

We investigate the color-magnitude distribution in the rich cluster AC 118 at z=0.31. The sample is selected by the photometric redshift technique, allowing to study a wide range of properties of stellar populations, and is complete in the K-band, allowing to study these properties up to a given galaxy mass. We use galaxy templates based on population synthesis models to translate the physical properties of the stellar populations - formation epoch, time-scale of star formation, and metallicity - into observed magnitudes and colors. In this way we show that a sharp luminosity-metallicity relation is inferred without any assumption on the galaxy formation scenario (either monolithic or hierarchical). Our data exclude significant differences in star formation histories along the color-magnitude relation, and therefore confirm a pure metallicity interpretation for its origin, with an early (z~5) formation epoch for the bulk of stellar populations. The dispersion in the color-magnitude diagram implies that fainter galaxies in our sample (K~18) ceased to form stars as late as z~0.5, in agreement with the picture that these galaxies were recently accreted into the cluster environment. The trend with redshift of the total stellar mass shows that half of the luminous mass in AC 118 was already formed at $z~2, but also that 20% of the stars formed at z<1.

16 pages, 10 figures. ApJ in press

References in corpus (5)

• The Transformation of Galaxies within the Large Scale Structure around a z=0.41 Cluster
• The colour magnitude relation for galaxies in the Coma cluster
• The Galaxy Population of Cluster RXJ0848+4453 at z=1.27
• Optical and Near-Infrared Structural Properties of Cluster Galaxies at $z\sim 0.3$
• Optical (VRI) Photometry in the Field of the Galaxy Cluster AC 118 at z=0.31

Cited by in corpus (4)

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• Transformations of galaxies in the environments of the cluster ABCG 209 at z~0.2
• Global Properties of the Rich Cluster ABCG 209 at z~0.2. Spectroscopic and Photometric Catalogue