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

arXiv:2607.14426 · astro-ph.GA, astro-ph.HE · Submitted 2026-07-15 · Read on arXiv

Joseph Whittingham

astro-ph.GA, astro-ph.HE

Submitted: 2026-07-15

Comments: 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

DOI: 10.25932/publishup-67622

License: http://creativecommons.org/licenses/by/4.0/

The gist: Mergers have long been understood to be a driver of galaxy and galaxy cluster evolution.

Terminology

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.

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