  The 5-9 keV spectrum of the inner ~100 kpc of the Perseus cluster measured by
XMM-Newton can be well described by an optically thin plasma emission model as
predicted by the APEC code, without any need for invoking a strong Ni
overabundance or the effects of resonant scattering. For the strongest 6.7 keV
line of He-like iron, the optical depth of the cluster, calculated using
observed density, temperature and abundance profiles, is of order 3. The lack
of evidence for resonant scattering effects implies gas motion in the core with
a range in velocities of at least half of the sound velocity. If this motion
has the character of small scale turbulence, then its dissipation would provide
enough energy to compensate for radiative cooling of the gas. The activity of
the supermassive black hole at the center of the cluster may be the driving
force of the gas motion.
