nIFTy Galaxy Cluster simulations IV: Quantifying the Influence of
  Baryons on Halo Properties
  Building on the initial results of the nIFTy simulated galaxy cluster
comparison, we compare and contrast the impact of baryonic physics with a
single massive galaxy cluster, run with 11 state-of-the-art codes, spanning
adaptive mesh, moving mesh, classic and modern SPH approaches. For each code
represented we have a dark matter only (DM) and non-radiative (NR) version of
the cluster, as well as a full physics (FP) version for a subset of the codes.
We compare both radial mass and kinematic profiles, as well as global measures
of the cluster (e.g. concentration, spin, shape), in the NR and FP runs with
that in the DM runs. Our analysis reveals good consistency (<= 20%) between
global properties of the cluster predicted by different codes when integrated
quantities are measured within the virial radius R200. However, we see larger
differences for quantities within R2500, especially in the FP runs. The radial
profiles reveal a diversity, especially in the cluster centre, between the NR
runs, which can be understood straightforwardly from the division of codes into
classic SPH and non-classic SPH (including the modern SPH, adaptive and moving
mesh codes); and between the FP runs, which can also be understood broadly from
the division of codes into those that include AGN feedback and those that do
not. The variation with respect to the median is much larger in the FP runs
with different baryonic physics prescriptions than in the NR runs with
different hydrodynamics solvers.
