Dynamics and Magnetization in Galaxy Cluster Cores Traced by X-ray Cold
  Fronts
  Cold fronts (CFs) - density and temperature plasma discontinuities - are
ubiquitous in cool cores of galaxy clusters, where they appear as X-ray
brightness edges in the intracluster medium, nearly concentric with the cluster
center. We analyze the thermodynamic profiles deprojected across core CFs found
in the literature. While the pressure appears continuous across these CFs, we
find that all of them require significant centripetal acceleration beneath the
front. This is naturally explained by a tangential, nearly sonic bulk flow just
below the CF, and a tangential shear flow involving a fair fraction of the
plasma beneath the front. Such shear should generate near-equipartition
magnetic fields on scales ~<50 pc from the front, and could magnetize the
entire core. Such fields would explain the apparent stability of cool-core CFs
and the recently reported CF-radio minihalo association.
