Snaith, Owain N.; Gibson, Brad K.; Brook, Chris B.; Courty, Stéphanie; Sánchez-Blázquez, P.; Kawata, Daisuke; Knebe, Alexander; Sales, Laura V.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 415, Issue 3, pp. 2798-2811.
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8
2011
Citations
11
Refereed citations
10
Description
Semi-analytic models (SAMs) are currently one of the primary tools with
which we model statistically significant ensembles of galaxies. The
underlying physical prescriptions inherent to each SAM are, in many
cases, different from one another. Several SAMs have been applied to the
dark matter merger trees extracted from the Millennium Run, including
those associated with the well-known Munich and Durham lineages. We
compare the predicted luminosity distributions of galaxy groups using
four publicly available SAMs, in order to explore a galactic environment
in which the models have not been explored to the same degree as they
have in the field or in rich clusters. We identify a characteristic
'wiggle' in the group galaxy luminosity function generated using the De
Lucia et al. SAM, which is not present in the Durham-based models,
consistent to some degree with observations. However, a comparison
between conditional luminosity functions of groups between the models
and observations suggests that neither model is a particularly good
match. The luminosity function wiggle is interpreted as the result of
the two-mode active galactic nucleus feedback implementation used in the
Munich models, which itself results in flattened magnitude gap
distribution. An associated analysis of the magnitude gap distribution
between first- and second-ranked group galaxies shows that while the
Durham models yield distributions with approximately equal luminosity
first- and second-ranked galaxies, in agreement with observations, the
De Lucia et al. models favour the scenario in which the second-ranked
galaxy is approximately 1 mag fainter than the primary, especially when
the dynamic range of the mock data is limited to 3 mag.