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A Study of the Observational and Data Analysis Techniques of Extragalactic Supernova Remnants: the Case of the Sculptor Group Galaxy NGC 300

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A Study of the Observational and Data Analysis Techniques of Extragalactic Supernova Remnants: the Case of the Sculptor Group Galaxy NGC 300 ResearchOnline@JCU This file is part of the following reference: Millar, William Charles (2012) A study of the observational and data analysis techniques of extragalactic supernova remnants: the case of the Sculptor Group Galaxy NGC 300. PhD thesis, James Cook University. Access to this file is available from: http://researchonline.jcu.edu.au/40011/ The author has certified to JCU that they have made a reasonable effort to gain permission and acknowledge the owner of any third party copyright material included in this document. If you believe that this is not the case, please contact [email protected] and quote http://researchonline.jcu.edu.au/40011/ A Study of the Observational and Data Analysis Techniques of Extragalactic Supernova Remnants: The Case of the Sculptor Group Galaxy NGC 300 Thesis submitted by William Charles MILLAR, M.A. in May 2012 for the degree of Doctor of Philosophy in the Centre for Astronomy James Cook University i Statement of Sources: I declare that this thesis is my own work and has not been submitted in any form for another degree or diploma at any university or other institution of tertiary education. Information derived from the published or unpublished work of others has been acknowledged in the text and a list of references given. This thesis contains material originally published in the journal Astrophysics and Space Sciences (Millar et al., 2011) and used here with permission from Springer-Verlag Publishing, license #2796170023827. This thesis contains material originally published in the Serbian Astronomical Journal (Millar et al., 2012) and is used here with copyrights retained. ii Contributors: The following people made contributions to this thesis: Name Chapter(s) Contribution(s) Signature Miroslav Filipovi´c All Principal Research Adviser. Coauthor of published papers. Graeme White All Research Adviser. Coauthor of published papers. Optical Spectra of Co-observer, contributed error Supernova Rem- analysis techniques. nant Candidates in NGC 300 Jeff Payne Optical Spectra of Coauthor of published paper, Supernova Rem- contributed object observation nant Candidates in selections. NGC 300 Thomas Pannuti Optical Spectra of Coauthor of published pa- Supernova Rem- per, original suggestion of nant Candidates in re-observing NGC 300 supernova NGC 300 remnant candidates from Blair & Long (1997). Evan Crawford Optical Spectra of Coauthor of published paper. Supernova Rem- nant Candidates in NGC 300 Wayne Staggs Optical Spectra of Coauthor of published paper, Supernova Rem- contributed Section 6.2.2. nant Candidates in NGC 300 iii Acknowledgements: From Chapter 6: I thank the Australian National University Research School of Astronomy and Astrophysics (RSAA) for the use of the 2.3 meter Advanced Technology Telescope (ATT) at Siding Spring Observatory (SSO), Australia. I used the NOAO (National Optical Astronomical Observatory) IRAF (Image Reduction and Analysis Facility) software package with Brent Miszalski’s “Planetary Nebula Extractor” task for IRAF, and the Figaro software package from the Starlink Project. IRAF is distributed by the NOAO which are operated by the Association of Universities for Research in Astronomy, Inc. (AURA), under cooperative agreement with the National Science Foundation (of the United States). I also used the KARMA software package from the Australian Telescope National Facility (ATNF). From Chapter 7: I gratefully acknowledge the generosity of Professor William Blair who provided the original CCD image files from the Blair & Long (1997) survey observations. Thanks also go to the Hubble Space Telescope (HST) archival team for their work in maintaining the archives thus making the telescope’s original data available to all. I used the Smithsonian Astrophysical Observatory’s (SAO) DS9 software package to process the images from both the original survey (Blair & Long, 1997) and from the Hubble Space Telescope. I also used software (“CCDOps”) from the Santa Barbara Imaging Group (SBIG). I thank the many people involved with the creation and development of these software programs and packages, and for making them available free of charge for use by astronomical researchers. This thesis makes use of data products from the Two Micron All Sky Survey (2MASS), which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Centre, funded by the National Aeronautics and Space Administration and the National Science Foundation. A grant from the Access to Major Research Facilities Program (AMRFP) from the Australian Nuclear Science and Technology Organisation provided for travel and lodging for observations at the South African Astronomical Observatory made during this thesis research. iv Dedications: Nothing worth doing can be done alone. I dedicate this work to my wife, Sheri Lynn Millar whose love, patience and understanding of the international travel and many long days at my desk made this advanced degree obtainable. I also dedicate this work to my father and mother, William Harold and Margie Jane Millar whose encouragement and support throughout my education has led to a successful career and an intense desire for lifelong learning. Abstract This thesis is based on multi-wavelength observations of supernova remnants in the nearby Sculptor Group galaxy NGC 300. A survey of the literature provides a set of observations of supernova remnants and candidate supernova remnants within NGC 300 in the X-ray, optical and radio spectral regions. A radio survey published by Payne et al. (2004) presents a number of new candidate supernova remnants. Blair & Long (1997) published an optical survey of supernova remnant candidates that have not been re-observed before this thesis and some of which had never had optical spectra taken. These two candidate sets were used to create a set of objects which were observed with the Advanced Technology Telescope at Siding Spring Observatory, using its moderate- resolution (< 5 A)˚ dual-beam spectrometer (Millar et al., 2011). Most of the radio sources of Payne et al. (2004) did not meet the accepted optical requirement of [S ii]:Hα > 0.4 while most of the optical sources from Blair & Long (1997) did meet this requirement. With multiple sources of observations of the optical supernova remnant candidates (Blair & Long, 1997) a problem appears. Comparing observations of the supernova remnant candidate labelled N300-S16 made by Blair & Long (1997) with those published in Millar et al. (2011) and also compared with an archival observation from the Hubble Space Telescope provides conflicting evidence as to the true nature of this particular object. Although there are known problems with the [S ii]:Hα > 0.4 criterion for identifying supernova remnants and there are reported resolutions to these problems, there appear to be more problems that may as yet be unrecognised. The spectral line flux levels from N300-S16 are low and this may cause a large error in spectral line flux measurement. This error source was investigated in Millar et al. (2011). The sulphur/oxygen gradient of NGC 300 has been studied (Christensen et al., 1997) and NGC 300 has a high level of diffuse ionised gas (Hoopes et al., 1996). There are no studies into how these factors may affect the [S ii]:Hα measurements for object identification. Telescope pointing errors, astrometry errors and seeing conditions all act adversely to the correct measurement of flux density from extragalactic candidate supernova remnants. The effects of these v vi ABSTRACT errors was investigated in particular for the N300-S16 object. I find that other observation techniques may be needed along with optical spectra – preferably very high-resolution optical imaging with space-based or ground- based adaptive optics capable telescopes – to confirm the true identity or even to validate the existence of some extragalactic supernova remnants. In the process of comparing Hubble Space Telescope images of NGC 300 with radio emission sources consistent with supernova remnants, I have found four locations where the Hubble Space Telescope’s images support the radio sources as being supernova remnants. Contents Abstract v 1 Introduction 1 1.1 AnOverviewofthisThesis ....................................... 3 2 Supernovae: The Progenitors of Supernova Remnants 7 2.1 Supernovae ................................................ 7 2.2 TypeISupernovae ............................................ 10 2.2.1 TypeIaSupernovae ....................................... 10 2.2.2 TypesIbandIcSupernovae................................... 12 2.3 TypeIISupernovae............................................ 13 2.3.1 TypeIISupernovaeSubtypes . .. 14 2.4 HistoricalSupernovae .......................................... 16 3 Supernova Remnants 21 3.1 TheTheoretical(Ideal)Model... ... .... ... .... ... .... ... .... ... .... 21 3.2 DeviationsfromtheIdealModel . ... .... ... .... ... .... ... .... ... .... 22 3.3 TheClassificationofSupernovaRemnants. 23 3.3.1 DistanceandDiameter...................................... 28 3.4 TheObservationalSampleBase.. ... .... ... .... ... .... ... .... ... .... 28 3.5 SupernovaRemnantObservables . .. 29 3.5.1 GammaRays........................................... 30 3.5.2 X-rays............................................... 32 vii viii CONTENTS 3.5.3 Ultraviolet ............................................ 33 3.5.4 Optical .............................................. 34 3.5.5 Infrared .............................................. 34 3.5.6 Radio ..............................................
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