A multi-wavelength study of super soft X-ray sources in the Magellanic Clouds
| dc.contributor.advisor | Meintjes, P. J. | |
| dc.contributor.author | Odendaal, Alida | |
| dc.date.accessioned | 2017-06-08T06:55:14Z | |
| dc.date.available | 2017-06-08T06:55:14Z | |
| dc.date.issued | 2012-02 | |
| dc.description.abstract | English: Supersoft X-ray Sources (SSS) form Cl, highly luminous class of objects that emit more Than ~ 90% of their energy in the supersoft X-ray band, i.e. below 0.5 keV. They are generally believed to consist of a white dwarf with a more massive binary companion, resulting in thermal time-scale mass transfer to the white dwarf and associated accretion. The high accretion rate of material onto the white dwarf is sufficient to drive nuclear burning and accompanying soft X-ray emission on the white dwarf surface, and may imply the presence of an accretion disc and significant mass outflow from some of these sources. However, SSS do not form a homogeneous class and also include objects like planetary nebulae, symbiotic novae and cataclysmic variables exhibiting nova outbursts. To investigate the phenomenon of accretion and the nature of possible mass outflow in SSS. a sample of 3 candidate sources in the Magellanic Clouds were identified for optical spectroscopic and X-ray studies: CAL 83, N67 and SMC 13. The galactic symbiotic nova RR Tel was also included in the study due to the evidence for an accretion disc implied by the double-peaked Raman-scattered 0 VI emission. Signatures of disc accretion and mass ejection in close binary supersoft sources (CBSS) like CAL 83, may provide evidence that such systems can evolve towards another class of binary system, namely the cataclysmic variables. Optical spectroscopic studies of CAL 83, NG7 and RR Tel were performed with the Southern African Large Telescope (SALT) and the SAAO l.9-m Telescope, and archived Chandm and XMM-Newton observations of the sources SMC 13 and CAL 83 were also analysed. The optical spectra of CAL 83 exhibit evidence of line broadening due to radial motion in an accretion disc, and a signature of possible disc outflows is also present. A search for periodicity in the X-ray data of CAL 83 revealed indication of consistent periodic modulations at P ~ 67 s, which could possibly be associated with the rotation period of a spun-up white dwarf. The presence of a fast rotating WD could provide a mechanism to explain the outflow inferred from the optical spectrum. The widths of nebular emission lines of the planetary nebula N67, as well as that of typical nebular lines in RR Tel are consistent with the known expansion velocities of nebulae surrounding the central objects in these systems. | en_ZA |
| dc.description.abstract | Afrikaans: Sagte X-straal bronne (SSS) vorm 'n klas van voorwerpe met 'n baie hoë helderheid, sodanig dat meer as ~ 90% van die energie in die sagte X-straal band (≤ 0.5 keV) uitgestraal word. Daar word in die algemeen geglo dat hierdie bronne bestaan uit 'n wit dwerg en 'n swaarder binêre geselster. wat aanleiding gee tot massa-oordrag na die wit dwerg op 'n termiese tydskaal, sowel as gepaardgaande akkresie. Die hoë akkresietempo van materiaal op die oppervlak van die wit dwerg is voldoende om kernbranding en gepaardgaande sagte X-straal emissie op die wit dwerg se oppervlak aan te dryf, en mag die teenwoordigheid van 'n akkresie-skyf en beduidende massa-uitvloei vanaf sommige van hierdie bronne impliseer. SSS vorm egter nie 'n homogene klas nie en sluit ook voorwerpe in soos planetêre newels, simbiotiese novas en kataklismiese veranderlikes wat nova-uitbarstings ondergaan. Om die verskynsel van akkresie en die aard van moontlike massa-uitvloei in SSS te ondersoek, is 'n seleksie van 3 kandidaatbronne in die Magellaanse Wolke geidentifiseer vir optiese spektroskopiese en X-straal studies: CAL 83, N67 en SMC 13. Die galaktiese simbiotiese nova RR Tel is ook in die studie ingesluit as gevolg van die bewyse vir 'n akkresle-skyf wat deur die dubbelpieke van die Raman-verstrooide 0 VI straling geïmpliseer word. Kenmerke van skyfakkresie en massa-uitwerping in binêre sagte X-straal bronne waarin die twee sterre nabyaan mekaar is, soos CAL 83, kan bewyse verskaf dat sulke sisteme kan ontwikkel na 'n ander klas van binêre sisteme, naamlike die kataklismiese veranderlikes. Optiese spektroskoplese studies van CAL 83, N67 en RR Tel is uitgevoer met die Suider-Afrikaanse Groot Teleskoop (SALT) en die SAAO 1.9-m Teleskoop, en waarnemings uit die argiewe van Chandra en XMM-Newton is ook geanaliseer. Die optiese spektra van CAL 83 toon bewyse van lynverbreding as gevolg van radiale beweging in 'n akkresieskyf, en 'n kenmerk van 'n moontlike skyfuitvloei is ook teenwoordig. 'n Soektog na periodisiteit in die X-straal data van CAL 83 het 'n aanduiding van konsekwente periodiese modulasies by P ~ 67 s opgelewer, wat moontlik geassosieer kan word met die rotasieperiode van 'n opgespinde wit dwerg. Die teenwoordigheid van 'n vinnig-roterende wit dwerg kan 'n meganisme verskaf wat die uitvloei wat deur die optiese spektrum geïmpliseer word: kan verduidelik. Die wydtes van die emissie-lyne van die planetêre newel N67, sowel as die tipiese newel-lyne in RR. Tel is in ooreenstemming met die bekende uitsettingsnelhede van die newels wat die sentrale voorwerpe in hierdie bronne omring. | af |
| dc.description.sponsorship | Square Kilometre Array (SKA) | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11660/6347 | |
| dc.language.iso | en | en_ZA |
| dc.publisher | University of the Free State | en_ZA |
| dc.rights.holder | University of the Free State | en_ZA |
| dc.subject | Supersoft X-ray source | en_ZA |
| dc.subject | Binary system | en_ZA |
| dc.subject | White dwarf | en_ZA |
| dc.subject | Rotation period | en_ZA |
| dc.subject | Accretion | en_ZA |
| dc.subject | Accretion disc | en_ZA |
| dc.subject | Spectroscopy | en_ZA |
| dc.subject | Emission line | en_ZA |
| dc.subject | Orbital modulation | en_ZA |
| dc.subject | Stellar evolution | en_ZA |
| dc.subject | Magellanic Clouds | en_ZA |
| dc.subject | X-ray sources, Galactic | en_ZA |
| dc.subject | White dwarf stars | en_ZA |
| dc.subject | Spiral galaxies -- Rotation | en_ZA |
| dc.subject | Dissertation (M.Sc. (Physics))--University of the Free State, 2012 | en_ZA |
| dc.title | A multi-wavelength study of super soft X-ray sources in the Magellanic Clouds | en_ZA |
| dc.type | Dissertation | en_ZA |