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Unraveling effects of anisotropy from low collisionality in the intracluster medium

Project description

Improved models could reveal hidden phenomena in the magnetised universe

Galaxy clusters are the largest known gravitationally bound structures in the universe. Their formation and evolution are tightly coupled to the evolution of the universe as a whole, which renders them important probes for testing cosmological models. A key feature of clusters is the intracluster medium – a heated, magnetised gas that fills the space between galaxies. Computational models typically treat the intracluster medium as a fluid demonstrating multi-particle collisions. These models lack the ability to describe small-scale phenomena that arise, for example, from anisotropic pressure. Funded by the Marie Skłodowska-Curie Actions programme, the LowCollICM project plans to develop a model that will incorporate such small-scale effects into large-scale cosmological simulations, thereby enhancing understanding of the magnetic universe.


Despite advances in both instrumental and computational capabilities, there still exists a mismatch between the observations of and theory describing galaxy clusters – the most massive gravitationally bound objects in the Universe. Galaxy clusters are used as probes for cosmological models and thus are important to our fundamental understanding of the Universe. Some differences clearly originate from an incorrect treatment of microphysical processes in large-scale cosmological simulations. This applies, in particular, to the intracluster medium (ICM). Particle collisions are rare in this hot, diffuse, magnetized plasma. In simulations the ICM is typically treated as a fully collisional fluid with an isotropic pressure. Hence, small-scale physics that stem, for example, from an anisotropic pressure, are missing. With this action the researcher will pave the way for the development of a model that allows for the incorporation of these small-scale effects into large-scale cosmological simulations. To achieve this, the researcher will implement anisotropic viscosity and thermal conduction in a next-generation, exascale simulation code. This code will then be used to conduct and analyze simulations of different aspects of the ICM covering both idealized, turbulent subvolumes and global isolated galaxy clusters. In doing so, the researcher will determine which effects are dynamically important, how they affect observables such as Faraday rotation measures and surface brightness discontinuities, and how to model them. Ultimately, future cosmological simulations employing a more accurate model will facilitate a more fundamental understanding of the magnetized Universe.



Net EU contribution
€ 174 806,40
20148 Hamburg

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Hamburg Hamburg Hamburg
Activity type
Higher or Secondary Education Establishments
Total cost
€ 174 806,40