Damped Lyman-alpha absorbers as a probe of stellar feedback
  We examine the abundance, clustering and metallicity of Damped Lyman-alpha
Absorbers (DLAs) in a suite of hydrodynamic cosmological simulations using the
moving mesh code AREPO. We incorporate models of supernova and AGN feedback, as
well as molecular hydrogen formation. We compare our simulations to the column
density distribution function at $z=3$, the total DLA abundance at $z=2-4$, the
measured DLA bias at $z=2.3$ and the DLA metallicity distribution at $z=2-4$.
Our preferred models produce populations of DLAs in good agreement with most of
these observations. The exception is the DLA abundance at $z < 3$, which we
show requires stronger feedback in $10^{11-12} \, h^{-1} M_\odot$ mass halos.
While the DLA population probes a wide range of halo masses, we find the
cross-section is dominated by halos of mass $10^{10} - 10^{11} \, h^{-1}
M_\odot$ and virial velocities $50 - 100 \;\mathrm{km/s}$. The simulated DLA
population has a linear theory bias of $1.7$, whereas the observations require
$2.17 \pm 0.2$. We show that non-linear growth increases the bias in our
simulations to $2.3$ at $k=1\; \mathrm{Mpc/}h$, the smallest scale observed.
The scale-dependence of the bias is, however, very different in the simulations
compared against the observations. We show that, of the observations we
consider, the DLA abundance and column density function provide the strongest
constraints on the feedback model.
