Modeling AGN Feedback in Cool-Core Clusters: The Formation of Cold
  Clumps
  We perform high-resolution (15-30 pc) adaptive mesh simulations to study the
impact of momentum-driven AGN feedback in cool-core clusters, focusing in this
paper on the formation of cold clumps. The feedback is jet-driven with an
energy determined by the amount of cold gas within 500 pc of the SMBH. When the
intra-cluster medium (ICM) in the core of the cluster becomes marginally stable
to radiative cooling, with the thermal instability to the free-fall timescale
ratio t_{TI}/t_{ff} < 3-10, cold clumps of gas start to form along the
propagation direction of the AGN jets. By tracing the particles in the
simulations, we find that these cold clumps originate from low entropy (but
still hot) gas that is accelerated by the jet to outward radial velocities of a
few hundred km/s. This gas is out of hydrostatic equilibrium and so can cool.
The clumps then grow larger as they decelerate and fall towards the center of
the cluster, eventually being accreted onto the super-massive black hole. The
general morphology, spatial distribution and estimated H{\alpha} morphology of
the clumps are in reasonable agreement with observations, although we do not
fully replicate the filamentary morphology of the clumps seen in the
observations, probably due to missing physics.
