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Properties of galaxy groups in the Sloan Digital Sky Survey -- I. The dependence of colour, star formation and morphology on halo mass


Weinmann, S M; van den Bosch, F C; Yang, X; Mo, H J (2006). Properties of galaxy groups in the Sloan Digital Sky Survey -- I. The dependence of colour, star formation and morphology on halo mass. Monthly Notices of the Royal Astronomical Society, 366(1):2-28.

Abstract

Using a large galaxy group catalogue constructed from the Sloan Digital Sky Survey Data Release 2, we investigate the correlation between various galaxy properties and halo mass. We split the population of galaxies in early-types, late-types and intermediate-types, based on their colour and specific star formation rate. At fixed luminosity, the late- (early-)type fraction of galaxies increases (decreases) with decreasing halo mass. Most importantly, this mass dependence is smooth and persists over the entire mass range probed, without any break or feature at any mass-scale. We argue that the previous claim of a characteristic feature on galaxy group scales is an artefact of the environment estimators used. At fixed halo mass, the luminosity dependence of the type fractions is surprisingly weak, especially over the range 0.25 ≲ L/L* ≲ 2.5: galaxy type depends more strongly on halo mass than on luminosity. In agreement with previous studies, the late- (early-)type fraction increases (decreases) with increasing halocentric radius. However, we find that this radial dependence is present in haloes of all masses probed (down to 1012 h−1 M⊙), while previous studies did not find any radial dependence in haloes with M≲ 1013.5 h−1 M⊙. We argue that this discrepancy owes to the fact that we have excluded central galaxies from our analysis. We also find that the properties of satellite galaxies are strongly correlated with those of their central galaxy. In particular, the early-type fraction of satellites is significantly higher in a halo with an early-type central galaxy than in a halo of the same mass but with a late-type central galaxy. This phenomenon, which we call ‘galactic conformity', is present in haloes of all masses and for satellites of all luminosities. Finally, the fraction of intermediate-type galaxies is always ∼20 per cent, independent of luminosity, independent of halo mass, independent of halocentric radius, and independent of whether the galaxy is a central galaxy or a satellite galaxy. We discuss the implications of all these findings for galaxy formation and evolution

Abstract

Using a large galaxy group catalogue constructed from the Sloan Digital Sky Survey Data Release 2, we investigate the correlation between various galaxy properties and halo mass. We split the population of galaxies in early-types, late-types and intermediate-types, based on their colour and specific star formation rate. At fixed luminosity, the late- (early-)type fraction of galaxies increases (decreases) with decreasing halo mass. Most importantly, this mass dependence is smooth and persists over the entire mass range probed, without any break or feature at any mass-scale. We argue that the previous claim of a characteristic feature on galaxy group scales is an artefact of the environment estimators used. At fixed halo mass, the luminosity dependence of the type fractions is surprisingly weak, especially over the range 0.25 ≲ L/L* ≲ 2.5: galaxy type depends more strongly on halo mass than on luminosity. In agreement with previous studies, the late- (early-)type fraction increases (decreases) with increasing halocentric radius. However, we find that this radial dependence is present in haloes of all masses probed (down to 1012 h−1 M⊙), while previous studies did not find any radial dependence in haloes with M≲ 1013.5 h−1 M⊙. We argue that this discrepancy owes to the fact that we have excluded central galaxies from our analysis. We also find that the properties of satellite galaxies are strongly correlated with those of their central galaxy. In particular, the early-type fraction of satellites is significantly higher in a halo with an early-type central galaxy than in a halo of the same mass but with a late-type central galaxy. This phenomenon, which we call ‘galactic conformity', is present in haloes of all masses and for satellites of all luminosities. Finally, the fraction of intermediate-type galaxies is always ∼20 per cent, independent of luminosity, independent of halo mass, independent of halocentric radius, and independent of whether the galaxy is a central galaxy or a satellite galaxy. We discuss the implications of all these findings for galaxy formation and evolution

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Item Type:Journal Article, refereed, original work
Communities & Collections:National licences > 142-005
Dewey Decimal Classification:530 Physics
Scopus Subject Areas:Physical Sciences > Astronomy and Astrophysics
Physical Sciences > Space and Planetary Science
Language:English
Date:11 February 2006
Deposited On:02 Nov 2018 07:35
Last Modified:31 Jul 2020 02:30
Publisher:Oxford University Press
ISSN:0035-8711
OA Status:Hybrid
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1111/j.1365-2966.2005.09865.x
Related URLs:https://www.swissbib.ch/Search/Results?lookfor=nationallicenceoxford101111j13652966200509865x (Library Catalogue)

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