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OATS-DAUT SEMINAR
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Speaker:
Nicola Menci (INAF-Osservatorio di Roma, I)
Title:
The environmental dependence of galaxy properties from
high to low redshift from cosmological galaxy formation models
Date: Wednesday, October 8th, 2008
Time: 12:00
Venue: Villa Bazzoni
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Abstract:
We compare the results from state-of-the-art
semi-analytic models of galaxy formation with spectroscopic
observations of the most distant galaxy clusters, observed in the
redshift range from 1 to 1.5.
We investigate the properties of the red sequence (RS) galaxies in
high-redshift clusters and compare them with those of the field.
In our model we find that
i) a well-defined, narrow RS is obtained
already by z=1.2; this is more populated than the field RS analogously
to what observed and predicted at z=0;
ii) the predicted RS colors and
width have average values of 1 and 0.15, respectively, with a
cluster-to-cluster variance. The width of the RS of cluster galaxies is
about 5 times lower than the corresponding field value;
iii) when the
RS galaxies are considered, the mass growth histories of field and
cluster galaxies at z=1.2 are similar, with 90% of the stellar mass of
RS galaxies at z=1.2 already formed at cosmic times t=2.5 Gyr, and 50%
at t=1 Gyr;
iv) The predicted distribution of stellar ages of RS
galaxies at z=1-1.5 are peaked at the value 3.7 Gyr for both cluster
and field; however, for the latter the distribution is significantly
skewed toward lower ages.
We discuss the physical origin and the significance
of the above results in the framework of cosmological galaxy
formation.
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contact: Francesco Calura (OATS)