The distribution of star-forming molecular gas in nearby spiral galaxies

Faustino Vieira, Helena 2024. The distribution of star-forming molecular gas in nearby spiral galaxies. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

The question of whether star formation is directly affected by the large-scale dynamics within a galaxy, or merely dependent on the local conditions of the interstellar medium (ISM), is a matter of long-standing debate. This is hindered by the difficulty in simultaneously probing the small-scales associated with the star formation process, and the large-scales which might regulate the formation and evolution of molecular clouds, where stars form. This Thesis describes a newly developed imaging technique which utilises the dust extinction at optical wavelengths to produce high-resolution maps of the dust (and gas) of nearby galaxies. The dust attenuation is determined by comparing optical data to a reconstructed stellar light model at each pixel. Here, this technique is first applied to the spiral M51 as a proof-of-concept, followed by a wider sample of nearby disc galaxies. This extinction imaging technique provides a foundation for an investigation into the distribution of the gas in nearby spiral galaxies at high resolution, with a particular focus on the impact of large-scale galactic environment. For that, an extensive catalogue of resolved clouds was extracted, enabling a statistical analysis of ISM properties. In this body of work, I find that there are clear changes in cloud populations between the centres and discs of galaxies, whilst differences between arm/inter-arm clouds are more subtle. Still, galactic environments within different galaxies do not always present the same physical conditions, and thus merely investigating cloud properties as a function of environment may result in loss of information on interesting galaxy-to-galaxy variations. Furthermore, the dust/gas images produced in this work have comparable resolution to JWST observations, enabling further studies into the correlation between, for example, the early, embedded phase of star formation and natal cloud properties.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Physics and Astronomy
Subjects:	Q Science > QC Physics
Uncontrolled Keywords:	ISM: clouds, dust, extinction, galaxies: ISM, galaxies: spiral
Funders:	Cardiff University
Date of First Compliant Deposit:	11 November 2024
Last Modified:	12 Nov 2024 09:57
URI:	https://orca.cardiff.ac.uk/id/eprint/173825

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