Gas flows in galaxy mergers
- 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 theIn 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.…
Author details: | Martin SparreORCiDGND, Joseph Whittingham, Mitali DamleORCiDGND, Maan H. HaniORCiD, Philipp RichterORCiDGND, Sara L. EllisonORCiD, Christoph PfrommerORCiDGND, Mark VogelsbergerORCiDGND |
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DOI: | https://doi.org/10.1093/mnras/stab3171 |
ISSN: | 1365-2966 |
Title of parent work (English): | Monthly notices of the Royal Astronomical Society |
Subtitle (English): | supersonic turbulence in bridges, accretion from the circumgalactic medium, and metallicity dilution |
Publisher: | Oxford Univ. Press |
Place of publishing: | Oxford |
Publication type: | Article |
Language: | English |
Date of first publication: | 2021/11/02 |
Publication year: | 2022 |
Release date: | 2024/02/22 |
Tag: | MHD; galaxies: interactions; galaxies: starburst; methods: numerical |
Volume: | 509 |
Issue: | 2 |
Number of pages: | 16 |
First page: | 2720 |
Last Page: | 2735 |
Funding institution: | European Research CouncilEuropean Research Council (ERC)European Commission [CRAGSMAN-646955]; NASA ATPNational Aeronautics & Space Administration (NASA) [16-ATP16-0167, 19-ATP19-0019, 19ATP19-0020, 19-ATP19-0167]; NSFNational Science Foundation (NSF) [AST-1814053, AST1814259, AST-1909831, AST-2007355]; William and Caroline Herschel Postdoctoral Fellowship Fund |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie |
DDC classification: | 5 Naturwissenschaften und Mathematik / 52 Astronomie / 520 Astronomie und zugeordnete Wissenschaften |
Peer review: | Referiert |
License (German): | Keine öffentliche Lizenz: Unter Urheberrechtsschutz |