ICMCS Seminar - Magnetised stratified turbulence and dynamo effect in the intracluster medium

Magnetic fields pervade the entire Universe, and its largest scales are no exception. At these scales are also found galaxy clusters – the natural endpoint of hierarchical structure formation – which formed only recently in the history of the Universe. Located at the nodes of the cosmic web, they are amongst the most massive gravitationally bound astrophysical systems in the Universe. Dark matter, magnetic fields, and a hot and diffuse plasma, called the intracluster medium (ICM), which shines almost exclusively in radio and X-ray wavelengths, permeate the space in between galaxies in clusters. Many questions related to the astrophysics of galaxy clusters remain unsolved, including the cooling catastrophe, the hydrostatic mass bias, the chemical enrichment and mixing, and the origin of cluster magnetic fields, to name but the most outstanding instances. Undoubtedly, a common ground between these diverse problems is the large-scale, fluid magnetised internal dynamics of the ICM of galaxy clusters. The latter remain, however, only poorly constrained because observing the ICM in the relevant frequency bands is intrinsically and technically very challenging.

In this talk, I will first substantially review these dynamics, physics, and astrophysics, pertaining to galaxy clusters and the ICM. I will then introduce the big open problems, mentioned above, to which ICM dynamics and energetics are most likely critical. Finally, I will present a few selected results obtained during my own PhD. The main goal of the latter has been to improve our understanding of a possible efficient driver of turbulent, magnetised internal dynamics in the ICM, the magneto-thermal instability (MTI) – a fundamental magnetohydrodynamical (MHD) process likely at play in the outskirts of galaxy clusters.