TY  - JOUR
A1  - Sparre, Martin
A1  - Whittingham, Joseph
A1  - Damle, Mitali
A1  - Hani, Maan H.
A1  - Richter, Philipp
A1  - Ellison, Sara L.
A1  - Pfrommer, Christoph
A1  - Vogelsberger, Mark
T1  - Gas flows in galaxy mergers
T2  - Monthly notices of the Royal Astronomical Society
N2  - In major galaxy mergers, the orbits of stars are violently perturbed, and gas is torqued to the centre, diluting the gas metallicity and igniting a starburst. In this paper, we study the gas dynamics in and around merging galaxies using a series of cosmological magnetohydrodynamical zoom-in simulations. We find that the gas bridge connecting the merging galaxies pre-coalescence is dominated by turbulent pressure, with turbulent Mach numbers peaking at values of 1.6-3.3. This implies that bridges are dominated by supersonic turbulence, and are thus ideal candidates for studying the impact of extreme environments on star formation. We also find that gas accreted from the circumgalactic medium (CGM) during the merger significantly contributes (27-51 percent) to the star formation rate (SFR) at the time of coalescence and drives the subsequent reignition of star formation in the merger remnant. Indeed, 19-53 percent of the SFR at z = 0 originates from gas belonging to the CGM prior the merger. Finally, we investigate the origin of the metallicity-diluted gas at the centre of merging galaxies. We show that this gas is rapidly accreted on to the Galactic Centre with a time-scale much shorter than that of normal star-forming galaxies. This explains why coalescing galaxies are not well-captured by the fundamental metallicity relation.
KW  - MHD
KW  - methods: numerical
KW  - galaxies: interactions
KW  - galaxies: starburst
Y1  - 2022
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/62586
SN  - 1365-2966
VL  - 509
IS  - 2
SP  - 2720
EP  - 2735
PB  - Oxford Univ. Press
CY  - Oxford
ER  -