This award funds a study of the linear polarization of the centimeter wavelength radiation from Active Galactic Nuclei (AGN) on the smallest scales. This is to be accomplished with the technique of polarization sensitive Very Long Baseline Interferometry (VLBI), whereby the linear polarization structure of compact radio sources may be determined on angular scales of milliarcseconds at multiple wavelengths. Dr. Roberts is one of the pioneers and leading investigators in VLBI polarization studies. At the distances of AGN, these small angular scales correspond to physical scales of light years. The linear polarization tells us about the magnetic field structure, radiation mechanisms, particle content, kinematics, and geometry of the radio jets produced by AGN, which will help us understand their structure and evolution. The ultimate goal of this work is to understand the mechanism which lies at the heart of AGN, currently thought to be accretion onto massive black holes.
