Encounters of Merger and Accretion Shocks in Galaxy Clusters and their
  Effects on Intracluster Medium
  Several types/classes of shocks naturally arise during formation and
evolution of galaxy clusters. One such class is represented by accretion
shocks, associated with deceleration of infalling baryons. Such shocks,
characterized by a very high Mach number, are present even in 1D models of
cluster evolution. Another class is composed of "runaway merger shocks", which
appear when a merger shock, driven by a sufficiently massive infalling
subcluster, propagates away from the main-cluster center. We argue that, when
the merger shock overtakes the accretion shock, a new long-living shock is
formed that propagates to large distances from the main cluster (well beyond
its virial radius) affecting the cold gas around the cluster. We refer to these
structures as Merger-accelerated Accretion shocks (MA-shocks) in this paper. We
show examples of such MA-shocks in 1D and 3D simulations and discuss their
characteristic properties. In particular, (1) MA-shocks shape the boundary
separating the hot intracluster medium (ICM) from the unshocked gas, giving
this boundary a "flower-like" morphology. In 3D, MA-shocks occupy space between
the dense accreting filaments. (2) Evolution of MA-shocks highly depends on the
Mach number of the runaway merger shock and the mass accretion rate parameter
of the cluster. (3) MA-shocks may lead to the misalignment of the ICM boundary
and the splashback radius.
