Magnetic Fields in Cooling Flow Clusters: A Critical View
  Shortly after the first results of Chandra and XMM-Newton appeared, many
researchers in the field abandoned the term "cooling flow clusters" in favor of
the name "cool core clusters". This change, I argue, has been causing damage by
promoting the view that there is no substantial cooling in these clusters. In
this contribution I discuss the following points, with emphasize on the last
one that deals with magnetic fields in cooling flow clusters. (1) Both
AGN-feedback and hot-gas cooling to form stars occur during galaxy formation as
well as in cooling flow clusters. Ignoring cooling of the intra-cluster medium,
as implied by the term "cool core", does not encourage comparative study of AGN
feedback in cooling flow clusters with that of galaxy formation. (2) The line
of thought that there is no cooling might lead to wrong questions and research
directions. (3) A key question in both cooling flow clusters and during galaxy
formation is the mode of accretion by the super massive black hole (SMBH). When
cooling is neglected only accretion from the hot phase remains. Accretion from
the hot phase, such as the Bondi accretion, suffers from some severe problems.
(4) When it is accepted that moderate quantities of gas are cooling, it becomes
clear that global heat conduction must be substantially suppressed. This does
not favor a globally ordered magnetic field. As well, it makes global heat
conduction unattractive.
