Journal Article

Central and satellite colours in galaxy groups: a comparison of the halo model and SDSS group catalogues

Ramin A. Skibba

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 392, issue 4, pages 1467-1474
Published in print February 2009 | ISSN: 0035-8711
Published online January 2009 | e-ISSN: 1365-2966 | DOI:
Central and satellite colours in galaxy groups: a comparison of the halo model and SDSS group catalogues

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Current analytic and semi-analytic dark matter halo models distinguish between the central galaxy in a halo and the satellite galaxies in halo substructures. It is expected that galaxy properties are correlated with host halo mass, and that central galaxies tend to be the most luminous, massive and reddest galaxies in haloes while the satellites around them are fainter and bluer. Using a recent halo-model description of the colour dependence of galaxy clustering (Skibba & Sheth), we investigate the colours of central and satellite galaxies predicted by the model and compare them to those of two galaxy group catalogues constructed from the Sloan Digital Sky Survey (SDSS; Yang et al.; Berlind et al.). In the model, the environmental dependence of galaxy colour is determined by that of halo mass, and the predicted colour mark correlations were shown to be consistent with SDSS measurements. The model assumes that satellites tend to follow a colour–magnitude sequence that approaches the red sequence at bright luminosities; the model's success suggests that bright satellites tend to be ‘red and dead’ while the star formation in fainter ones is in the process of being quenched. In both the model and the SDSS group catalogues, we find that at fixed luminosity or stellar mass, central galaxies tend to be bluer than satellites. In contrast, at fixed group richness or halo mass, central galaxies tend to be redder than satellites, and galaxy colours become redder with increasing mass. We also compare the central and satellite galaxy colour distributions, as a function of luminosity and as a function of richness, in the model and in the two group catalogues. Except for faint galaxies and small groups, the model and both group catalogues are in very good agreement.

Keywords: methods: analytical; methods: statistical; galaxies: clusters: general; galaxies: formation; galaxies: haloes; large scale structure of the universe

Journal Article.  6389 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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