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Investigating high velocity HI clouds in the Milky Way halo
thesisposted 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  and the Galactic All-Sky Survey (GASS) McClure-Griffiths et al. . 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.