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Abstract The physical mechanisms responsible for bar formation and destruction in galaxies remain a subject of debate. While we have gained valuable insight into how bars form and evolve from isolated idealized simulations, in the cosmological domain, galactic bars evolve in complex environments, with mergers and gas accretion events occurring in the presence of the turbulent interstellar medium with multiple star formation episodes, in addition to coupling with their host galaxies’ dark matter halos. We investigate the bar formation in 13 Milky Way–mass galaxies from the Feedback in Realistic Environments (FIRE-2) cosmological zoom-in simulations. 8 of the 13 simulated galaxies form bars at some point during their history: three from tidal interactions and five from internal evolution of the disk. The bars in FIRE-2 are generally shorter than the corotation radius (mean bar radius ∼1.53 kpc), have a wide range of pattern speeds (36–97 km s−1kpc−1), and live for a wide range of dynamical times (2–160 bar rotations). We find that the bar formation in FIRE-2 galaxies is influenced by satellite interactions and the stellar-to-dark-matter mass ratio in the inner galaxy, but neither is a sufficient condition for bar formation. Bar formation is more likely to occur, with the bars formed being stronger and longer-lived, if the disks are kinematically cold; galaxies with high central gas fractions and/or vigorous star formation, on the other hand, tend to form weaker bars. In the case of the FIRE-2 galaxies, these properties combine to produce ellipsoidal bars with strengthsA2/A0∼ 0.1–0.2.
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This content will become publicly available on January 3, 2026
Linking Dark and Stellar Substructure in the Illustris TNG-50 Simulation
Dark matter plays a crucial role in shaping the structure and development of galaxies. Understanding how dark matter interacts with visible matter provides key insights into the fundamental processes that drive galaxy formation and evolution. The Illustris TNG-50 simulation provides detailed modeling of the formation and evolution of galaxies from shortly after the Big Bang and accounts for a wide range of physical processes that influence this formation. This offers the opportunity to investigate how galaxies and their structures evolve over time and the role of dark matter in this process. Using a two-point correlation study of baryonic matter in Milky Way-like galaxies in TNG-50, we seek to understand if two-point correlation signals change over time. More specifically, we aim to determine whether specific length scales of dark matter structures leave detectable imprints on a galaxy's stellar distribution. Additionally, we will investigate whether galaxies in TNG-50 exhibit asymmetric structures in stars and/or dark matter, and examine how these asymmetries evolve before and after major merger events. This is achieved by developing code to identify the symmetry axes of disk galaxies in TNG-50, aiming to explore whether the principal axes of dark matter and stellar distributions align or if any misalignment changes over cosmic time.
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- Award ID(s):
- 2319428
- PAR ID:
- 10645134
- Publisher / Repository:
- volume 245 of American Astronomical Society Meeting Abstracts, 311.01, January 2025
- Date Published:
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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