Probing extragalactic dust through gamma-ray burst afterglows

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Probing extragalactic dust through gamma-ray burst afterglows

Please use this identifier to cite or link to this item: http://hdl.handle.net/10355/12011

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dc.contributor.advisor Li, Aigen en_US
dc.contributor.author Liang, Sunlin, 1978- en_US
dc.date.accessioned 2011-11-04T13:54:55Z
dc.date.available 2011-11-04T13:54:55Z
dc.date.issued 2010 en_US
dc.date.submitted 2010 Summer en_US
dc.identifier.other LiangS-073010-D520 en_US
dc.identifier.uri http://hdl.handle.net/10355/12011
dc.description The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. en_US
dc.description Title from PDF of title page (University of Missouri--Columbia, viewed on October 28, 2010). en_US
dc.description Thesis advisor: Dr. Aigen Li. en_US
dc.description Vita. en_US
dc.description Includes bibliographical references. en_US
dc.description Ph. D. University of Missouri--Columbia 2010. en_US
dc.description Dissertations, Academic -- University of Missouri--Columbia -- Physics. en_US
dc.description.abstract Gamma-Ray Bursts (GRBs) are the most powerful explosions in the universe and a very interesting phenomenon in themselves. The gamma-rays and the X-ray flashes (XRFs) are the manifestations of the most violent, cataclysmic explosions in the Universe. GRBs are followed by so-called afterglow emission detected in lower energy bands and on longer timescales, e.g. Xray, UV, optical, near-infrared, radio emissions from a few hundred seconds to a few months. The following thesis does not deal with the GRB phenomenon itself but it is studying their environment and host galaxies through optical spectroscopy and using them as light sources In the distant universe. This thesis is divided into six parts. The first chapter of the thesis discusses the importance of dust on exploring the host galaxies of GRBs. In the second chapter, we present a detailed study on the obscuration and reddening by dust in GRB host galaxies. We propose a novel approach - "Drude" model to derive the GRB host extinction law. We also present the general dust extinction models and explain why our "Drude" model is more favorable. With the template extinction laws all self-contained, and the capability of revealing extinction laws differing from the conventional ones, it is shown that this is a powerful approach in modeling the afterglow SEDs to derive GRB host extinction. In the third chapter, we select GRB070802 at z= 2.45 (which shows clear evidence for the 2175Å extinction bump) and GRB050904 at z= 6.29, the 3rd most distant GRB observed to date and fit their afterglow spectra to determine the extinction of their host galaxies, with an emphasis on the 2175Å extinction feature at high redshifts. We find that their extinction curves differ substantially from that of the Milky Way, the Small and Large Magellanic Clouds, the 2175Å extinction feature appears to be also present in GRB050904 at z=6.29. In the fourth and fifth chapter, we present a study of the dust properties for a large sample (33 objects) of long-GRB host galaxies at z [lesser than] 2.0 and another large sample (27 objects) at z [greater than] 2.0, respectively. From the derived strength of the far-UV extinction rise, strength of the 2175Å extinction, the total-to selective extinction ratio RV , host galaxy visual extinction AV , dust composition and the mass weighted mean dust sizes of all 60 GRBs, we find no evidence of evolution of the dust properties (extinction, sizes and abundance) on redshifts. The thesis ends with summary, outlook and the references. en_US
dc.format.extent xx, 151 pages en_US
dc.language.iso en_US en_US
dc.publisher University of Missouri--Columbia en_US
dc.subject.lcsh Gamma ray bursts en_US
dc.subject.lcsh Cosmic dust -- Optical properties en_US
dc.subject.lcsh Astronomical spectroscopy en_US
dc.subject.lcsh Galaxies -- Spectra en_US
dc.title Probing extragalactic dust through gamma-ray burst afterglows en_US
dc.type Thesis en_US
thesis.degree.discipline Physics en_US
thesis.degree.grantor University of Missouri--Columbia en_US
thesis.degree.name Ph. D. en_US
thesis.degree.level Doctoral en_US
dc.relation.ispartofcommunity University of Missouri-Columbia. Graduate School. Theses and Dissertations. Dissertations. 2010 Dissertations


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