Numerical simulations of Milky Way galaxies: stellar and gas dynamics

Duran Camacho, Eva 2024. Numerical simulations of Milky Way galaxies: stellar and gas dynamics. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Star formation has traditionally been assumed to be a universal process based on observational findings suggesting consistent characteristics across different regions. However, detailed observations of individual star-forming regions within galaxies reveal deviations from these universal behaviours. This raises critical questions about whether the chaotic nature of the interstellar medium (ISM) or the large-scale dynamics of the host galaxy play a significant role in regulating star formation. The Milky Way offers an ideal laboratory to investigate this relationship, but our internal viewpoint complicates our knowledge of the Galactic structure. Although the spiral arms and central bar of the Milky Way are well-recognised features, the exact configuration of the galaxy remains unclear. While advanced observational facilities like ALMA, Herschel, GAIA, and JWST provide improved resolutions, interpreting these observations within the larger galactic framework remains a challenge. Numerical models are commonly used to test our theories, but most existing models only vaguely resemble the Milky Way, focusing on general properties like mass and rotation curve rather than replicating its specific features. These limitations reduce the utility of such models when analysing observational data. Therefore, there is a need for a more accurate model that dynamically evolves and mimics the key structures our Galaxy. This is essential to improve our understanding of star formation and ISM dynamics in the Milky Way. The main aim of this thesis is to address these gaps by developing a self-consistent numerical model of the Milky Way using the AREPO code. In Chapter 2, I present a suite of 15 Milky Way-type galaxy models that I generated and compared to observational data from 12CO and HI emissions using longitude-velocity plots. From these models, I identified a best-fitting model that successfully reproduces the overall structure of the Milky Way, including specific observed features. With a best-fit model identified, I conducted in Chapter 3 a detailed analysis of the kinematic properties of the stellar and gaseous components. This analysis focused on how large-scale galactic dynamics, could influence smaller-scale gas kinematics. In particular, I investigated how gas agglomeration and disruption processes occur, specially surrounding the spiral structure, which could potentially set the initial conditions for star formation. Finally, I investigated periodic wave-like structures or ‘wiggles’ in the position-velocity maps of the model, which resemble features seen in Galactic observations. I present in Chapter 4 the preliminary results on the investigation of their origins and kinematic signatures across position-position and position-velocity space. This study shows that these ’wiggles’ are strongly linked to both radial and tangential velocity residuals and are influenced by the dynamic nature of the spiral arms themselves. These are transient structures continuously evolving, shaped by the complex interplay between gas dynamics and gravitational forces within the galaxy.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Physics and Astronomy
Subjects:	Q Science > QC Physics
Uncontrolled Keywords:	dynamics, Galaxies: structure, ISM: star formation, Galaxies: simulations, Galaxies: Milky Way, ISM: structure
Funders:	College Funded
Date of First Compliant Deposit:	16 December 2024
Last Modified:	16 Dec 2024 11:34
URI:	https://orca.cardiff.ac.uk/id/eprint/174741

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