Journal
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Volume 503, Issue 3, Pages 3113-3133Publisher
OXFORD UNIV PRESS
DOI: 10.1093/mnras/staa2952
Keywords
methods: numerical; ISM: structure; galaxies: evolution; galaxies: interactions; galaxies: starburst; galaxies: star formation
Categories
Funding
- FAS Division of Science, Research Computing Group at Harvard University
- National Science Foundation (NSF) [1516374]
- Harvard Institute for Theory and Computation, through their Visiting Scholars Program
- NSERC
- National Sciences and Engineering Research Council of Canada (NSERC) Graduate Scholarship
- European Research Council (ERC) [695671]
- STFC
- Vanier Canada Graduate Scholarship
- Simons Foundation
- NSF [1715847, 1911233, 1455342]
- NationalAeronautics Space Agency (NASA) [80NSSC18K0562, 1589742]
- Division Of Astronomical Sciences
- Direct For Mathematical & Physical Scien [1911233, 1516374] Funding Source: National Science Foundation
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The study shows that close encounters in interacting galaxies significantly increase cool gas budgets, leading to enhanced star formation. Additionally, galaxies with high global star formation rates experience intense nuclear star formation enhancement in the central region, while those with low global SFR are suppressed in the central region.
We investigate the spatial structure and evolution of star formation and the interstellar medium (ISM) in interacting galaxies. We use an extensive suite of parsec-scale galaxy-merger simulations (stellar mass ratio = 2.5:1), which employs the 'Feedback In Realistic Environments-2' model (FIRE-2). This framework resolves star formation, feedback processes, and the multiphase structure of the ISM. We focus on the galaxy-pair stages of interaction. We find that close encounters substantially augment cool (HI) and cold-dense (H-2) gas budgets, elevating the formation of new stars as a result. This enhancement is centrally concentrated for the secondary galaxy, and more radially extended for the primary. This behaviour is weakly dependent on orbital geometry. We also find that galaxies with elevated global star formation rate (SFR) experience intense nuclear SFR enhancement, driven by high levels of either star formation efficiency (SFE) or available cold-dense gas fuel. Galaxies with suppressed global SFR also contain a nuclear cold-dense gas reservoir, but low SFE levels diminish SFR in the central region. Concretely, in the majority of cases, SFR enhancement in the central kiloparsec is fuel-driven (55 per cent for the secondary, 71 per cent for the primary) - while central SFR suppression is efficiency-driven (91 per cent for the secondary, 97 per cent for the primary). Our numerical predictions underscore the need of substantially larger, and/or merger-dedicated, spatially resolved galaxy surveys - capable of examining vast and diverse samples of interacting systems - coupled with multiwavelength campaigns aimed to capture their internal ISM structure.
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