2002/06/30 by P. Merluzzi, F. La Barbera, M. Massarotti +2 · 2 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Brightest cluster galaxy #Elliptical galaxy #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy cluster #Galaxy formation and evolution #Lenticular galaxy #Redshift #Star formation #Statistical Mechanics and Entropy #Stellar mass #astro-ph
paper · pdf · doi:10.1086/374636
published as Astrophys.J. 589 (2003) 147-156 · 16 pages, 10 figures. ApJ in press
arxiv created 2003/02/07 · openalex publication_date 2003/05/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
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 us to study a wide range of properties of stellar populations, and is complete in the K band, allowing us 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, timescale of star formation, and metallicity—into observed magnitudes and colors. The distributions of galaxies in color-magnitude space thus map into distributions in physical parameter space. This is achieved by means of a statistical procedure that constrains the photometric properties of AC 118 galaxies to reproduce those of a nearby rich cluster once evolved at z ~ 0. 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 formation redshift 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 and also that 20% of the stars formed at z < 1.