Merging galaxies and clusters: Insights into the role of magnetic fields and the physics of radio relics

Abstract

Mergers have long been understood to be a driver of galaxy and galaxy cluster evolution. They release tremendous amounts of gravitational potential energy - ~$10^{59}$ and ~$10^{64}$ ergs in galaxies and clusters, respectively - which is dissipated in powerful shock waves. In galaxies especially, the strong tidal effects can have profound effects on the remnant morphology. Although the modelling of mergers has a long history, it is only recently that it has been fully appreciated just how sensitive they are to a range of factors, including the existence of circumgalactic media (CGM), accretion along filaments, and pre-existing magnetic fields. Modelling these aspects in a cosmologically-consistent manner necessitates the use of high-resolution cosmological magnetohydrodynamic (MHD) simulations. In this work, we use such simulations to investigate two distinct merger-related phenomena: i) magnetic fields in galaxy mergers, and ii) the origin of radio relics in galaxy clusters.

PhD Thesis, University of Potsdam (2025), xii + 228 pages. Ch. 3-5 reprint arXiv:2011.13947, arXiv:2301.13208, and arXiv:2411.11947, resp. Ch. 6 is expanded in arXiv:2604.06302. Ch. 7 describes major revisions to the CREST and AREPO shock finder implementations; cite this work for these developments