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Detection of Magnetic Fields and Diffuse Radio Emission in Abell 3667 and Other Rich Southern Clusters of Galaxies

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Detection of Magnetic Fields and Diffuse Radio Emission in Abell 3667 and Other Rich Southern Clusters of Galaxies LI b. s'o Detection of Magnetic Fields and Diffuse Radio Emission in Abell 3667 and other Rich Southern Clusters of Galaxies Melanie J ohnst on-Hollitt Department of Physics & Mathematical Physics tlniversity of Adelaide A thesis subm'itted'in fulfi'Iment of the requ'irements for the degree of Doctor of Ph'ilosophA July 2003 @) 2003 Melanie Johnston-Hollitt Statement of OriginalitY This thesis is the result of work undertaken between 1998 and 2002in the Astrophysics Group in the Department of Physics and Mathematical Physics at the University of Adelaide and the csIRo Australia Telescope National Facility. 843 MHz data from the Molonglo Observatory Synthesis Telescope and R-band CCD imaging of 43667 were kindly provicled by Dr Dick Hunstead and the Astrophysics Department at the University of Sydney' 20 and 13cm ATCA data for the northwest region of 43667 taken by Röttgering et al. (1gg7) were obtained from the ATNF archive and re-analysed in conjunction with new data presented here for the southern region' The MTRTAD software package was used for the data reduction and analysis of ATCA data, while programs from the KARMA suite were used for visualisation. The AJPS software package was used for the reduction and analysis of VLA data. The 2clfdr software suite was used for the initial reduction of the 43667 spectroscopic data, and I am grateful to the 2dF Galaxy redshift team for allowing the use of their spectral templates. Radio spectral analysis of the diffuse radio emission in 43667 was performed using the SyNAGE+1 package in collaboration with Matteo Murgia of the IRA, Bologna, Italy. X-ray analysis of the ROSAT PSPC archival observations of 43667 was trndertaken using the ESO MIDAS software with the assistance of Federica Govoni of the IRA, Bologna, Italy. The optical spectra for 43667 were collected by Dr Terry Bridges under the 2dF service observations program for the project ZdF obseruati,ons of the Abell cluster A3667 for which the investigators were Johnston-Hollitt (PI), Corbett and Hunstead. The tar- get selection and observation files were completed with the assistance of Dr Elizabeth Corbett. Reduction of the final spectra rvas performed with some assitance from Dr Elizabeth Corbett and the work was significantly enhanced by the guidance of Dr Dick Hunstead. I VLA observations of the source 09L7+75 are from the ongoing observational pro- gram High Resoluti,on Obseruations of the Relic 0917+75, by Johnston-Hollitt (pI) and Clarke. Data reduction was performed with the assistance of Dr Tracy Clarke. The interpolated Galactic RM maps are generated using MATLAB. Coding of the maps was performed in collaboration with Christopher Hollitt and the work owes a great deal to thoughtful discussions with both Christopher Hollitt and Prof. Ron Ekers. \ /ith the above exceptions, this thesis contains no material which has been presented for another degree at this or any other university and, to the best of my knowledge and belief, contains no copy or paraphrase ofwork published by another person, except where duly acknowledged in the text. I give consent to this copy of my thesis, when deposited in the University Library, being available for loan and photocopying. Nlelanie J ohnston-Hollitt JuIv 2003 Acknowledgements When I look back across my candidature I realise that I have been extremely privileged to have worked with such a large group of excellent researchers. I am profoundly grate- ful to have been given the opportunity to pursue my dream of studying at least a small part of this mysterious lJniverse. I have a great many people to thank for assisting me in this endeavour. Throughout the course of my thesis I have been lucky to have such a diverse selection of advisors from whom to seek guidance. My principal supervisor Prof. Ron Ekers pro- vided the initial concept for the project and though the thesis took a fairly crooked path from the original intent to its final destination, Ron was throughout the entire process' a source of guidance, inspiration and fantastic amounts of information. Though I often found myself "thror,vn in the deep end", on the few times I forgot how to swim R.on did not let me drown. I feel enormously fortunate to have worked with Ron as I have learnt far more about what it is to be an astrophysicist than is simply contained in this thesis' The assistance of my co-supervisor Dr Dick Hunstead was in many ways complemen- tary to that of Ron. I lvas continually amazed by the enthusiasm that Dick displayed for both this and other projects. Dick's assistance lvith the optical analysis in this project has been invaluable and though I complained at the time, his ever-ready green pen for correcting ancl proof-reading abstracts, posters, papers and this thesis has been a tremendous service. My university supervisor Dr Roger CIay gave great support as a referee for many fund- ing applications, provided funding for travel in Australia and was a critical reader of the manuscript. Also through Roger I gained a great deal of invaluable high level teaching experience. I am greatly indebted to my many collaborators for both their assistance ancl profes- sionalism toward all work, be it for this thesis or otherwise. In particular I wish to thank Dr Tracy Clarke, Dr Elizabeth Corbett, Dr Chris Fluke, Dr Neil Killeen, Dr Matteo Murgia, Dr Haida Liang, Dr Mark Wieringa, Dr Bruce Dawson, Jose Bellido, Prof. Jim Rose, Dr Wayne Christiansen and Matt Fleenor. There are many people at the ATNF who not only made my work easier but who tv Acknowledgements made me want to be doing it. I thank; Dr Dave Rayner for all his assistance with the vagaries of MIRTAD ancl for providing a balanced perspective on the HWWS 98 committee; Dr Bob Sault for providing insight to mosaicing and polarimetry; Dr Neil "read the manual" Killeen for answering stupid questions about MTTITAD imaging and rotation measures; Elaine Pacey for alr,vays making I sure I got to see Ron, for help with all matters administrative and for keeping everything in Ron's office running basically smoothly! There was many a time Elaine tried to steer me away from Tim Tams for lunch, a course doomed to failure, but I appreciated the effort anyway - at least I was convinced to wear my shoes with the laces tied!! I thank Ms. Helen Sim for all the media related assistance, for her ever fascinating conversations on all topics from Australian science policy to the particular perspective in the works of Jan Van Eck, but most of all her friendship. Thanks are also extended to Dr Lister Staveley- Smith, Dr Jessica Chapman, Dr Tasso Tzioumis, Dr Torry Wong, Dr Roopesh ojha, Dr Mike Kesteven, Anne Barends, and Betty Siegman (like Elaine, gone but not forgotten). Staying in the N4arsfield Lodge was a great pleasure due to the very funky Vicki Drazen- ovic and Elsa - the place has never been so nice!! On my many trips to the ATCA at Narrabri I was always pleased to have the assistance of the 'wonderful team of unsung heroes who kept the telescope running and made vis- itors feel 'welcome. In particular the tireless work of Robin Wark ensuring that both duty astronorners and new observers are provided with all the relevant information ancl then arriving at 2:00 am in the middle of a thunder storm "just to make sure", must be acknowledged. (I am especially grateful that Robin never put the hideous photo of me as a vac student up on the photo wall!). I thank Dr Dave McConnell and Robin for their patience during the times I had to call in the middle of the night or early morning to get advice on fixing all manner of antenna problems - it was a great learning expe- rience! For endless trips to the airport and assistance with all matters administrative I thank Jo Houldsworth, Kylee Forbes, Anni Reynolds and her predecessor Tina Earl. No thesis in astrophysics is ever completed without the help of various "computer gu- rus" so I would like to extend my profound thanks to several people both at Adelaide and in Sydney. At ATNF I am indebted to Dr Shaun "the legend" A-y for always having a cheerful solution to even the most obscure computer matter, Dr Richard Gooch for all his assistance with the Karma package and in particular, for putting the three map overlay into Kvier,r', Malte Viarquarding for trying to teach me AIPS** and helping with image overlaying, Andrew Wright for coding the RM database search pages, ancl Vince Mclntyre and Henrietta NIay for always finding me disk space at very short notice! At Adelaide I am profoundly grateful for the help of Dr Ken Simpson and Ian Borchardt who stopped me beating my head against the department's machines a number of times by providing ingenious ways of getting around the bizarre computer setup at Adelaide. Though I did not frequent my offices much either in Adelaide or Sydney, I am grateful Acknowledgements V to my ofÊce mates, Hayley Bignall, Tracy Getts and Daniel Mitchell for not being too surprised when I did show up, for not stealing my desks and generally being good company. Additionally, I would like to thank Hayley for doing my remote observations while I was overseas. I thank Bob Hurn at Adelaicle for periodically letting me take over his office, computer, printer, scanner and telephone when there was nowhere else for me to work. During the course of my thesis, I have been privileged to be able to travel extensively not just between the University of Aclelaide and the ATNF but also to overseas insti- tutions on five separate occasions.
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