Multiphase cooling flows

I discuss the multiphase nature of the intracluster medium whose neglect can lead to overestimates of the baryon fraction of clusters by up to a factor of two. The multiphase form of the cooling flow equations are derived and reduced to a simple form for a wide class of self-similar density distributions. It is shown that steady-state cooling flows are \emph{not} consistent with all possible emissivity profiles which can therefore be used as a test of the theory. In combination, they provide strong constraints on the mass distribution within the cooling radius.