Macquarie University
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Investigating high velocity HI clouds in the Milky Way halo

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posted on 2022-03-28, 16:07 authored by Natasha Marshall
Understanding the gas exchange dynamics in the Milky Way galaxy is important in under-standing Galactic evolution and the ongoing fuelling of star formation. Determining the structure of neutral hydrogen high velocity clouds in the halo can provide insight into how the gas within the Halo feeds star formation in the Galaxy. We examine the 21cm Hi emission spectra from 84 sightlines in the Milky Way halo using data from both the Southern Weak Intensity Survey of H i (SWISH) Moss and McClure-Griffiths [2017] and the Galactic All-Sky Survey (GASS) McClure-Griffiths et al. [2009]. This thesis presents a semi automatic calibration method for analysis of SWISH sightlines, with the inclusion of Bayesian Gaussian modelling. We find a population of low column density gas previously undetected by GASS and discuss these preliminary results in the context of the overall structure of the neutral gas in the Galactic Halo.


Table of Contents

Introduction -- 2. Survey of weak intensity southern HI (SWISH) -- 3. Data reduction and analysis -- 4. Results and discussion -- 5. Conclusions and future directions.


Bibliography: pages 61-66 Theoretical thesis.

Awarding Institution

Macquarie University

Degree Type

Thesis MRes


MRes, Macquarie University, Faculty of Science and Engineering, Department of Physics and Astronomy

Department, Centre or School

Department of Physics and Astronomy

Year of Award


Principal Supervisor

Joanne Dawson


Copyright Natasha Marshall 2019. Copyright disclaimer:




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