TERMALNO ZRAČENJE OSTATAKA SUPERNOVIH U RADIO-PODRUČJU

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TERMALNO ZRAČENJE OSTATAKA SUPERNOVIH U RADIO-PODRUČJU

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dc.contributor.advisor Urošević, Dejan
dc.contributor.author Onić, Dušan
dc.date.accessioned 2013-10-08T10:08:16Z
dc.date.available 2013-10-08T10:08:16Z
dc.date.issued 2013
dc.identifier.uri http://hdl.handle.net/123456789/3051
dc.description.abstract The evolution of supernova remnants is linked to the propagation of a collisionless shock wave, formed during the initial expansion of high-velocity supernova ejecta through the interstellar environment. Theoretical studies of shock waves are very important for the analysis of supernova remnants, as well as processes in the interstellar medium in general. In this doctoral dissertation, some theoretical results based on the magnetohydrodynamical theory of shock waves are presented, with special emphasis on ideal radiative magnetohydrodynamics for the optically thick case. Particularly, solutions for the case when jump in adiabatic index and/or ratio of gas to total pressure is allowed, are discussed. The main hypothesis of this dissertation is that thermal bremsstrahlung radiation at radio continuum frequencies can provide a signi cant contribution in the case of several Galactic supernova remnants. This hypothesis can give a natural explanation for nearly concave up radio continuum spectra of several Galactic supernova remnants that are expanding in the environment with higher than average density. In this context, it is important to identify the existence of the possible indicators of ensemble of thermal electrons at su ciently low temperatures and su ciently high densities so that the thermal bremsstrahlung radiation linked to a particular remnant could be observed at radio continuum frequencies (vicinity, interaction or expansion through the molecular cloud, presence of the cooled thermal X-ray electrons during the post Sedov-Taylor phases, detection of low-frequency turnovers associated with thermal absorption linked to the remnant, detection in H , identi cation of radio recombination lines linked to the remnant, etc). The signi cant presence of thermal component could theoretically explain radiospectral indices less than 0.5 measured for several evolutionary older supernova remnants, (mainly of mixed-morphology class) that expand in the high density region. Actually, these smaller radio-spectral indices, under the assumption of simple power law, would represent a natural manifestation of a signi cant fraction of thermal emission at radio continuum frequencies. However, present knowledge of the radio continuum spectra of Galactic supernova remnants is still not determined precisely enough for any de nite conclusions to be made about the inherent thermal radio-emission from supernova remnants. A thorough analysis is only possible in the case of three Galactic supernova remnants (3C396, IC443, 3C391) for which the thermal contribution is determined despite high associated uncertainties. New observations in the near future will lay the groundwork for making rmer conclusions about the existence of the so-called radio thermally active supernova remnants. This dissertation highlights the importance of observations of supernova remnants in X and -rays, and multiwavelength analysis is general. Besides, it suggests a possible detection of -rays from supernova remnant 3C434.1 based on the observations made by Fermi. en_US
dc.description.provenance Submitted by Slavisha Milisavljevic (slavisha) on 2013-10-08T10:08:16Z No. of bitstreams: 1 Onic_Dusan_disertacija.pdf: 10679680 bytes, checksum: 50273e440027531fc02b8c442f508e9e (MD5) en
dc.description.provenance Made available in DSpace on 2013-10-08T10:08:16Z (GMT). No. of bitstreams: 1 Onic_Dusan_disertacija.pdf: 10679680 bytes, checksum: 50273e440027531fc02b8c442f508e9e (MD5) Previous issue date: 2013 en
dc.format.mimetype PDF en_US
dc.language.iso sr en_US
dc.publisher Beograd en_US
dc.title TERMALNO ZRAČENJE OSTATAKA SUPERNOVIH U RADIO-PODRUČJU en_US
mf.author.birth-date 1982-10-04
mf.author.birth-place Beograd en_US
mf.author.birth-country Srbija en_US
mf.author.residence-state Srbija en_US
mf.author.citizenship Srpsko en_US
mf.author.nationality Srpsko en_US
mf.subject.area Astronomy en_US
mf.subject.keywords supernova remnants, interstellar medium, shock waves en_US
mf.subject.subarea Astrophysics en_US
mf.contributor.committee Lihi, Denis
mf.contributor.committee Arbutina, Bojan
mf.contributor.committee Vukotić, Branislav
mf.university.faculty Mathematical en_US
mf.document.references 255 en_US
mf.document.pages 147 en_US
mf.document.location Beograd en_US
mf.document.genealogy-project No en_US
mf.author.parent Želimir en_US
mf.university Belgrade en_US

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