253 research outputs found
The evolution of the colour-magnitude relation and of the star formation activity in galaxy clusters since z~0.8
We present recent results on the evolution of the colour-magnitude relation
and of the star formation activity in galaxy clusters since z~0.8. Results are
based on the ESO Distant Cluster Survey (EDisCS) - an ESO large programme aimed
at the study of cluster structure and cluster galaxy evolution over a
significant fraction of cosmic time - and are discussed in the framework of the
current standard paradigm of structure formation.Comment: 8 pages, 5 figure, to appear in ASP Conference Series (Proceedings of
the 1st Subaru International Conference "Panoramic Views of Galaxy Formation
and Evolution", held in Japan, 10-15 December 2007
The connection between galaxy structure and quenching efficiency
Using data from the SDSS-DR7, including structural measurements from 2D
surface brightness fits with GIM2D, we show how the fraction of quiescent
galaxies depends on galaxy stellar mass , effective radius , fraction
of band light in the bulge, , and their status as a central or
satellite galaxy at . For central galaxies we confirm that the
quiescent fraction depends not only on stellar mass, but also on . The
dependence is particularly strong as a function of , with
. This appears to be driven by a simple dependence on
over the mass range , and is qualitatively
similar even if galaxies with are excluded. For satellite galaxies,
the quiescent fraction is always larger than that of central galaxies, for any
combination of , and . The quenching efficiency is not
constant, but reaches a maximum of for galaxies with and kpc. This is the same region of parameter
space in which the satellite fraction itself reaches its maximum value,
suggesting that the transformation from an active central galaxy to a quiescent
satellite is associated with a reduction in due to an increase in
dominance of a bulge component.Comment: 17 pages, 28 figures, accepted to MNRAS. Catalog available at
http://quixote.uwaterloo.ca/~mbalogh/downloads/Omand_published.fit
Evolution of Elliptical Galaxies: The Multiphase Model
We present a multiphase model for the evolution of elliptical galaxies.
Diffuse gas, molecular clouds, stars and remnants are taken into account.
Cloud--cloud collisions and stimulated processes are the main causes of star
formation. The occurrence of winds driven by Supernovae is considered, and the
evolution of the system is computed also after the first wind, allowing for
further star formation from the restored gas. The evolution of the abundances
of 15 elements or isotopes is followed with detailed stellar nucleosynthesis.
Stellar lifetimes are taken into account and a new IMF has been adopted. The
gas removal due to the Supernovae explosions depends on the galactic mass and
the presence of dark matter; the subsequent wind episodes are crucial to the
intergalactic gas enrichment. Good agreement is obtained for current SNs rates,
Star Formation Rate and gas masses when compared to the available data.Comment: 32 pages, Tex. 12 Figures can be sended if requeste
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