Nature and nurture in galaxy formation simulations
by
Marcel Haas(Leiden University)
→
Europe/Stockholm
FA32
FA32
Description
The OverWhelmingly Large Simulation (OWLS) set of cosmological
N-body/SPH runs follow the formation of galaxies in a representative
volume of the universe for a large range of physical and numerical
parameters. Input physics, such as the prescriptions for star formation,
supernova feedback, AGN feedback, chemical enrichment, cooling and
cosmology, as well as numerical parameters such as box size and mass
resolution are varied one by one, in order to investigate their
influence on the resulting synthetic universe and its constituents.
We will show stellar masses, star formation rates and related properties
of a large numbers of galaxies, simulated at high resolution. We relate
the differences in correlations between these parameters to the
differences in input physics. We find that the implementation of
supernova and AGN feedback are crucial for the star formation rates of
galaxies. Depending on the way they are simulated and the numeric values
of the parameters, an enormous variety of SFRs (at fixed stellar mass)
may result from the self-regulation of the star formation by the
feedback processes. Interestingly, the details of the treatment of high
density gas and the parameters of the star formation law are largely
unimportant for these quantities, whereas they do affect the
morphological appearance significantly.
Most popular definitions of environmental parameters will be shown to
mainly be a measure of dark matter halo mass, using the Millennium
Simulation and semi-analytic galaxy formation models on top of those.
When environmental parameters are scaled to virial parameters of the
host halo, the environment measure is independent of halo mass, though
most properties of the simulated galaxies seem insensitive to these
measures of large scale environment. Being a central galaxy or a
satellite does make a difference, due to the stripping of low density
gas in the haloes of infalling smaller galaxies.
