On the nature of local instabilities in rotating galactic coronae and cool cores of galaxy clusters

Abstract

A long-standing question is whether radiative cooling can lead to local condensations of cold gas in the hot atmospheres of galaxies and galaxy clusters. We address this problem by studying the nature of local instabilities in rotating, stratified, weakly magnetized, optically thin plasmas in the presence of radiative cooling and anisotropic thermal conduction. For both axisymmetric and non-axisymmetric linear perturbations we provide the general equations that can be applied locally to specific systems to establish whether they are unstable and, in case of instability, to determine the kind of evolution (monotonically growing or over-stable) and the growth rates of unstable modes. We present results for models of rotating plasmas representative of Milky Way-like galaxy coronae and cool-cores of galaxy clusters. It is shown that the unstable modes arise from a combination of thermal, magnetothermal, magnetorotational and heat-flux-driven buoyancy instabilities. Local condensation of cold clouds tends to be hampered in cluster cool cores, while it is possible under certain conditions in rotating galactic coronae. If the magnetic field is sufficiently weak the magnetorotational instability is dominant even in these pressure supported systems.

arXiv comment16 pages, 8 figures, ApJ in press. Minor changes from previous version

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Cited by in corpus (10)

• A Global Model For Circumgalactic and Cluster-Core Precipitation
• Cool circumgalactic gas of passive galaxies from cosmological inflow
• The effect of rotation on the thermal instability of stratified galactic atmospheres - I. Local analysis
• The effect of rotation on the thermal instability of stratified galactic atmospheres - II. The formation of High Velocity Clouds
• Inflow of low-metallicity cool gas in the halo of the Andromeda galaxy
• Magnetorotational instability in cool cores of galaxy clusters
• Stability Analysis of Convection in the Intracluster Medium
• Searching for rotation in X-COP galaxy clusters
• On the Helium fingers in the intracluster medium
• Effect of Composition Gradient on Magnetothermal Instability Modified by Shear and Rotation