Open group seminar: Francisco Ley (University of Wisconsin-Madison)

11:00 am–12:00 pm ERC 583

Host: Emily Lichko

Francisco Ley (University of Wisconsin-Madison) "Heating Galaxy Clusters at Smallest Scales, or How to Overtake Turbulence?"

Turbulence driven by supermassive black hole activity, gravitational infall, and galaxy motions is an attractive energy source for heating the intracluster plasma (ICM) in galaxy clusters. However, how this energy dissipates into heat is unclear, since the ICM is weakly collisional. In this talk, I will present an energization mechanism capable of heating the plasma via magnetic pumping at kinetic scales. I use numerical simulations of a plasma subject to a periodic variation of the mean magnetic field, where these cyclic variations generate pressure anisotropies which produce an effective viscosity that can either heat or cool the plasma. I will show that when the pressure anisotropy is regulated by kinetic microinstabilities such as Mirror and Firehose, heating can be effectively retained after one pump cycle. The efficiency at which this mechanism acts depends on the level of macroscopic turbulence and how fast microinstabilities can be excited and saturate. Our results show that this process can be relevant in dissipating and distributing turbulent energy at kinetic scales in the ICM.

Event Type


Nov 18