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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 559532.0, MPI für Astronomie / Publikationen_mpia
A multiscale approach to environment and its influence on the colour distribution of galaxies
Authors:Wilman, D. J.; Zibetti, S.; Budavári, T.
Date of Publication (YYYY-MM-DD):2010
Title of Journal:Monthly Notices of the Royal Astronomical Society
Journal Abbrev.:Monthly Notices of the Royal Astronomical Society
Issue / Number:3
Start Page:1701
End Page:1720
Review Status:not specified
Audience:Not Specified
Abstract / Description:We present a multiscale approach for measurements of galaxy density, applied to a volume-limited sample constructed from the Sloan Digital Sky Survey Data Release 5 (SDSS DR5). We populate a rich parameter space by obtaining independent measurements of density on different scales for each galaxy. This parametrization purely relies on observations and avoids the implicit assumptions involved, e.g. in the construction of group catalogues. As the first application of this method, we study how the bimodality in galaxy colour distribution (specifically u - r) depends on multiscale density. The u - r galaxy colour distribution is described as the sum of two Gaussians (a red and a blue one) with five parameters: the fraction of red galaxies (fred) and the position and width of the red and blue peaks (μred,μblue,σred and σblue). Galaxies mostly react to their smallest scale (<0.5Mpc) environments: in denser environments red galaxies are more common (larger fred), redder (larger μred) and with a narrower distribution (smaller σred), while blue galaxies are redder (larger μblue) but with a broader distribution (larger σblue). There are residual correlations of fred and μblue with 0.5-1Mpc scale density, which imply that total or partial truncation of star formation can relate to a galaxy's environment on these scales. Beyond 1Mpc (0.5Mpc for μred) there are no positive correlations with density. However fred anticorrelates with density on >2Mpc scales at fixed density on smaller scales, and μred anticorrelates with density on >1Mpc scales. We examine these trends qualitatively in the context of the halo model, utilizing the properties of haloes within which the galaxies are embedded, derived by Yang et al. and applied to a group catalogue. This yields an excellent description of the trends with multiscale density, including the anticorrelations on large scales, which map the region of accretion on to massive haloes. Thus we conclude that galaxies become red only once they have been accreted on to haloes of a certain mass. The mean colour of red galaxies μred depends positively only on <0.5Mpc scale density, which can most easily be explained if correlations of μred with environment are driven by metallicity via the enrichment history of a galaxy within its subhalo, during its epoch of star formation.
Free Keywords:methods: statistical; galaxies: evolution; galaxies: fundamental parameters; galaxies: haloes; galaxies: statistics; galaxies: stellar content
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://adsabs.harvard.edu/abs/2010MNRAS.406.1701W [ID No:1]
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