abstract
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We investigate the population of z=3 damped Lyman alpha absorbers (DLAs) in a
recent series of high resolution galaxy formation simulations. The simulations
are of interest because they form at z=0 some of the most realistic disk
galaxies to date. No free parameters are available in our study: these have
been fixed by physical and z=0 observational constraints, and thus our study
provides a genuine consistency test. The precise role of DLAs in galaxy
formation remains in debate, but they provide a number of strong constraints on
the nature of our simulated bound systems at z=3 because of their coupled
information on neutral H I densities, kinematics, metallicity and estimates of
star formation activity.
Our results, without any parameter-tuning, closely match the observed
incidence rate and column density distributions of DLAs. Our simulations are
the first to reproduce the distribution of metallicities (with a median of
Z_{DLA} = Z_{solar}/20) without invoking observationally unsupported mechanisms
such as dust biasing. This is especially encouraging given that these
simulations have previously been shown to have a realistic 0