This thesis addresses two fundamental questions in astrophysics: (i) To what extent is environment a driver of galaxy evolution? And (ii) How does hierarchical structure formation affect the galaxy environment? The former is addressed by examining the environments of starburst galaxies, the latter by examining clusters undergoing major mergers with focus placed on the efficacy of ??cold fronts?? in identifying systems that have recently undergone a major merger - an essential first step to understanding their impact. For the first of these studies, the 2dFGRS was exploited to select large samples of starburst galaxies. These were used to derive measurements of the local and large-scale environments, clustering properties, and morphologies of starburst galaxies. It is found local environment is most germane in terms of a starburst triggering mechanism, with the starburst galaxies showing an excess of close (<20 kpc) neighbours with comparable luminosity/mass, while 20-30% exhibit a morphology consistent with them being involved in an ongoing tidal/merger interaction. On large scales (5-15 Mpc), the starburst galaxies were found to be much less clustered compared to the overall 2dFGRS population, and were not preferentially found in rich clusters with just over half residing in low to intermediate luminosity groups. However, in a number of cases, evidence for obvious local environmental influences was lacking, indicating starbursts can also be internally driven. For the latter study, the Chandra, archive was used to select a sample of clusters exhibiting ??cold front?? features. Selection required the presence of significant density jumps (>1.5 at the lower 90% CI) in the intracluster medium and for the gas on the denser side of the front to be cooler. From this sample, the clusters Abell 1201, Abell 2163, RXJ1720.1+2638, and Abell 3667 were targeted for comprehensive spectroscopic follow-up at optical wavelengths using the 3.9m Anglo Australian and 6.5m Multiple Mirror Telescopes. Using 321 spectroscopically confirmed members for Abell 1201, 550 for Abell 3667 and 491 for Abell 2163 it is shown that these clusters contain substructure which can be directly related to the cold fronts, whilst for 335 confirmed members in RXJ1720.1+2638 promising evidence exists for merger activity related to the cold front. Despite the range of different types of cold fronts and substructures detected, it is clear that cold fronts are robust signposts of merger activity.
| Identifer | oai:union.ndltd.org:ADTP/257940 |
| Date | January 2008 |
| Creators | Owers, Matthew Scott, Physics, Faculty of Science, UNSW |
| Publisher | Publisher:University of New South Wales. Physics |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | http://unsworks.unsw.edu.au/copyright, http://unsworks.unsw.edu.au/copyright |
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