On the Dynamical Stability of Weakly-Collisional Plasmas with Thermal and Composition Gradients

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• Martin Pessah (Niels Bohr Institute, Copenhagen, Denmark)
• Monday 05 November 2012, 16:00-17:00
• MR14, Centre for Mathematical Sciences, Wilberforce Road, Cambridge.

If you have a question about this talk, please contact Jérôme Guilet.

Over the last decade, substantial efforts have been devoted to understanding the stability properties, transport phenomena, and long-term evolution of weakly-collisional, magnetized plasmas which are stratified in temperature. The insights gained by these studies have contributed to our current understanding of the processes that determine the physical evolution and observational properties of the intra-cluster medium (ICM) permeating galaxy clusters. Motivated by the need to obtain a more complete picture of the dynamical properties of the ICM , I will discuss the stability of a weakly-collisional atmosphere stratified in both temperature and composition. I will show that the plasma can be subject to a wide variety of unstable modes which include modfications to the magnetothermal instability (MTI), the heat-flux-driven buoyancy instability (HBI), and overstable gravity modes previously studied in homogeneous media. I will discuss the astrophysical implications of these findings for a representative galaxy cluster where helium has sedimented.

This talk is part of the DAMTP Astrophysics Seminars series.

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