TY  - JOUR
A1  - Whittingham, Joseph
A1  - Sparre, Martin
A1  - Pfrommer, Christoph
A1  - Pakmor, Rüdiger
T1  - The impact of magnetic fields on cosmological galaxy mergers
BT  - I. Reshaping gas and stellar discs
JF  - Monthly notices of the Royal Astronomical Society
N2  - Mergers play an important role in galaxy evolution. In particular, major mergers are able to have a transformative effect on galaxy morphology. In this paper, we investigate the role of magnetic fields in gas-rich major mergers. To this end, we run a series of high-resolution magnetohydrodynamic (MHD) zoom-in simulations with the moving-mesh code arepo and compare the outcome with hydrodynamic simulations run from the same initial conditions. This is the first time that the effect of magnetic fields in major mergers has been investigated in a cosmologically consistent manner. In contrast to previous non-cosmological simulations, we find that the inclusion of magnetic fields has a substantial impact on the production of the merger remnant. Whilst magnetic fields do not strongly affect global properties, such as the star formation history, they are able to significantly influence structural properties. Indeed, MHD simulations consistently form remnants with extended discs and well-developed spiral structure, whilst hydrodynamic simulations form more compact remnants that display distinctive ring morphology. We support this work with a resolution study and show that whilst global properties are broadly converged across resolution and physics models, morphological differences only develop given sufficient resolution. We argue that this is due to the more efficient excitement of a small-scale dynamo in higher resolution simulations, resulting in a more strongly amplified field that is better able to influence gas dynamics.
KW  - MHD
KW  - methods: numerical
KW  - galaxies: interactions
KW  - galaxies: magnetic
KW  - fields
Y1  - 2021
U6  - https://doi.org/10.1093/mnras/stab1425
SN  - 0035-8711
SN  - 1365-2966
VL  - 506
IS  - 1
SP  - 229
EP  - 255
PB  - Oxford Univ. Press
CY  - Oxford
ER  -