Abstract

In dilute, magnetized plasmas exchanges of heat across magnetic field lines are strongly suppressed. The anisotropic character of heat conduction, together with large-scale temperature gradients, destabilises otherwise stable flows via the magneto-thermal instability (MTI) and generates turbulence. The MTI could be relevant in the intra-cluster medium in the outskirts of galaxy clusters, where it may supply a source of the observed turbulence, and in the plasma of hot accretion flows around black holes, where the MTI can interact with the magneto-rotational instability (MRI) to produce complex dynamics. In this talk, I will summarize recent findings on the MTI saturation mechanism and present a general theory that provides scalings and estimates for the turbulent levels appropriate for galaxy clusters. I will then address the question of how the MTI is modified in the presence of shear and rotation, and attempt to characterise the possible interplay between the MTI and the MRI in hot accretion flows.