Multi-frequency synchrotron self-compton models for the brightness temperature problem in compact extra-galactic radio sources [Elektronische Ressource] / presented by Olivia Tsang

Dissertation submitted to theCombined Faculties for the Natural Sciences and Mathematicsof the Ruperto-Carola University of Heidelberg, Germanyfor the degree ofDoctor of Natural Sciencespresented byOlivia Tsang, MSci Physicsborn in Hong KongOral examination: 25 July 2007Multi-frequency Synchrotron Self-Compton Modelsfor the Brightness Temperature Problemin Compact Extra-galactic Radio SourcesReferees:Prof. Dr. John G. KirkProf. Dr. Stefan WagnerAbstractFlux variations in quasars and BL Lac objects over a time scale of a day orless suggest an extremely high brightness temperature in these sources, which can-not be explained by conventional synchrotron theory. This work addresses the issueof extreme brightness temperature by applying synchrotron theory to unconventionalelectron distributions.We consider a scenario in which relativistic electrons are continuously injectedinto the emission region. In the first approximation, we assume the electrons aremonoenergetic for simplicity. This approximation is insufficient when modelling thespectrum of S5 0716+714, we therefore modified the electron injection spectrum to onewhich is a double power law in energy. This retains the low radio frequency spectralcharacteristics of monoenergetic electrons, which extends to higher frequencies as apower law. To complete the study of the intrinsic properties of synchrotron emissionfrom monoenergetic electrons, we also examine their circular polarisation.