Mid-infrared interferometry of nearby active galactic nuclei [Elektronische Ressource] / presented by Konrad R. W. Tristram

Dissertationsubmitted to theCombined Faculties for the Natural Sciences and for Mathematicsof the Ruperto-Carola University of Heidelberg, Germanyfor the degree ofDoctor of Natural Sciencespresented byDiplom-Physicist Konrad R. W. Tristramborn in Freiburg im Breisgau, GermanythOral examination: July 25 , 2007Mid-infrared interferometryof nearby Active Galactic NucleiVersion 2.22007 August 27Online Publication VersionReferees: Prof. Dr. Klaus Meisenheimer Dr. Immo AppenzellervAbstract: Activegalacticnucleiarepoweredbytheaccretionofmatterontosupermassiveblack holes in the centre of galaxies. In unified schemes, warm, obscuring dust and gas ina torus play a major role for the different manifestations of such nuclei. The differences arethoughttodependontheviewingangleswithrespecttothedustdistribution, whichabsorbsthe nuclear light and re-emits it in the infrared.The scientific goal of this thesis is to reveal the nature of the nuclear mid-infrared sourcein a few nearby active galaxies in order to explore the innermost dust distribution on parsecscales. As this requires angular resolutions of < 20mas, interferometric observations withthe MIDI instrument at the Very Large Telescope Interferometer were performed.TheprimarytargetistheCircinusgalaxy, aprototypeSeyfert2galaxy. Themodellingofthe interferometric data revealed that warm dust (T ∼300K) is located in two components:inadiskwitharadiusof0.