The Three Hundred project: The Gizmo-Simba runs
  We introduce \textsc{Gizmo-Simba}, a new suite of galaxy cluster simulations
within \textsc{The Three Hundred} project. \textsc{The Three Hundred} consists
of zoom re-simulations of 324 clusters with $M_{200}\gtrsim 10^{14.8}M_\odot$
drawn from the MultiDark-Planck $N$-body simulation, run using several
hydrodynamic and semi-analytic codes. The \textsc{Gizmo-Simba} suite adds a
state-of-the-art galaxy formation model based on the highly successful {\sc
Simba} simulation, mildly re-calibrated to match $z=0$ cluster stellar
properties. Comparing to \textsc{The Three Hundred} zooms run with
\textsc{Gadget-X}, we find intrinsic differences in the evolution of the
stellar and gas mass fractions, BCG ages, and galaxy colour-magnitude diagrams,
with \textsc{Gizmo-Simba} generally providing a good match to available data at
$z \approx 0$. \textsc{Gizmo-Simba}'s unique black hole growth and feedback
model yields agreement with the observed BH scaling relations at the
intermediate-mass range and predicts a slightly different slope at high masses
where few observations currently lie. \textsc{Gizmo-Simba} provides a new and
novel platform to elucidate the co-evolution of galaxies, gas, and black holes
within the densest cosmic environments.
