  The electron mean free path in the intracluster medium (ICM) of galaxy
clusters is much larger than the gyroradius; thus, heat is transported
anisotropically along magnetic field lines. We show that the intracluster
medium is unstable to the magnetothermal instability (MTI) using MHD
simulations with anisotropic thermal conduction. As a result of the MTI, we
find that the temperature profile of the ICM can be substantially modified on
timescales of several billion years while the magnetic field is amplified by
dynamo action up to more than fifty times the original energy. We also show
that the instability drives field lines to become preferentially radial leading
to conduction that is a highly efficient fraction of the Spitzer conductivity.
As such, we present the first self-consistent calculation of the effective
thermal conductivity in the ICM.
