Removing Cool Cores and Central Metallicity Peaks in Galaxy Clusters
  with Powerful AGN Outbursts
  Recent X-ray observations of galaxy clusters suggest that cluster populations
are bimodally distributed according to central gas entropy and are separated
into two distinct classes: cool core (CC) and non-cool core (NCC) clusters.
While it is widely accepted that AGN feedback plays a key role in offsetting
radiative losses and maintaining many clusters in the CC state, the origin of
NCC clusters is much less clear. At the same time, a handful of extremely
powerful AGN outbursts have recently been detected in clusters, with a total
energy ~10^{61}-10^{62} erg. Using two dimensional hydrodynamic simulations, we
show that if a large fraction of this energy is deposited near the centers of
CC clusters, which is likely common due to dense cores, these AGN outbursts can
completely remove CCs, transforming them to NCC clusters. Our model also has
interesting implications for cluster abundance profiles, which usually show a
central peak in CC systems. Our calculations indicate that during the CC to NCC
transformation, AGN outbursts efficiently mix metals in cluster central
regions, and may even remove central abundance peaks if they are not broad
enough. For CC clusters with broad central abundance peaks, AGN outbursts
decrease peak abundances, but can not effectively destroy the peaks. Our model
may simultaneously explain the contradictory (possibly bimodal) results of
abundance profiles in NCC clusters, some of which are nearly flat, while others
have strong central peaks similar to those in CC clusters. A statistical
analysis of the sizes of central abundance peaks and their redshift evolution
may shed interesting insights on the origin of both types of NCC clusters and
the evolution history of thermodynamics and AGN activity in clusters.
