The impact of black hole seeding in cosmological simulations
  Most cosmological simulations of galaxy evolution include active galactic
nucleus (AGN) feedback, typically seeding black holes with masses of $\geq
10^5\, h^{-1}\, \rm{M}_{\odot}$ when the dark matter halo exceeds a given
threshold mass. Taylor & Kobayashi (2014) introduced a new model, which seeds
black holes at $10^3\, h^{-1}\, \rm{M}_{\odot}$ based on gas properties alone,
and motivated by the channel of black hole formation due to the collapse of the
most massive first stars in the Universe. We compare the black hole mass when
the dark matter halo mass is $10^{10}\, h^{-1}\, \rm{M}_{\odot}$ between the
different seeding methods. We find that seeding based upon gas properties gives
a distribution of black hole masses with $\langle \log M_{\rm{BH}} {/
\rm{M}_{\odot}} \rangle = (5.18 \pm 0.54)$ when dark matter halo mass is
$10^{10}\, h^{-1}\, \rm{M}_{\odot}$, consistent with the {seeding criteria}
used in other simulations. However, the evolution of individual galaxies can be
strongly affected by the different seeding mechanisms. We also find that the
mean value of the distribution of black hole masses at a given halo mass
evolves over time, with higher masses at higher redshifts, indicative of
downsizing. Our results can inform more physically motivated black hole and AGN
feedback models in cosmological simulations and semi-analytic models.
