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http://hdl.handle.net/11375/24153
Title: | Star Formation in the Galactic Context: A Quantitative Study |
Authors: | Benincasa, Samantha |
Advisor: | Wadsley, James Couchman, Hugh |
Department: | Physics and Astronomy |
Publication Date: | 2018 |
Abstract: | The processes that impact star formation operate not only on molecular cloud scales, but on the scales of full galaxies. This implies that the full galactic environment is crucial to the study of star formation. As observations and empirical relations on this scale become increasingly more detailed, simulations lag behind, still unable to explain the origins behind the Kennicutt-Schmidt relation, for example. We investigate star formation in the full galactic context through a series of isolated galaxy simulations. We favour purposefully controlled setups so that we can perform a systematic study of the drivers of star formation and the theoretical underpinning behind the formation of bound structures that lead to star formation. We demonstrate the key role of pressure in regulating the star formation rate. We extend this to galaxies that include far-ultraviolet (FUV) heating implemented using radiative transfer. These simulations, the first of their kind, show that FUV heating is not sufficient to regulate star formation. Generally, we find that the scale height is a key driver in maintaining vertical hydrostatic balance. Simulated galaxies that do not resolve the scale height will be unable to explain fundamental relationships, becoming increasingly similar to semi-analytic models where all important relationships are imposed. We develop a new method to study the formation of bound structure: we seed turbulent perturbations of known wavelength and velocity in quiet galaxy disks. The linear theory is a good approximation for the early phases of structure growth, which has a finite window to occur; the shear timescale. We find that clumps can form not just through central condensation but through rotation-driven fission and the fragmentation of tidal tails, a novel result. We find that these bound clouds, the direct progenitors of star clusters, do not exceed $\sim10^9$ M$_{\odot}$ in galaxies of gas mass up to $\sim5\times10^{10}$ M$_{\odot}$. |
URI: | http://hdl.handle.net/11375/24153 |
Appears in Collections: | Open Access Dissertations and Theses |
Files in This Item:
File | Description | Size | Format | |
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Benincasa_Samantha_M_2018September_PHD.pdf | 4.69 MB | Adobe PDF | View/Open |
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