Southern hemisphere gamma-ray blazars

The detection of high energy gamma-ray emission from AGN has resulted in several emission mechanisms and emission sites being proposed. One such emission mechanism relies on the inverse Compton effect. In this effect low energy photons are upscattered to high energies due to collisions with high energy electrons. This would suggest a possible link between radio synchrotron emission (providing high energy electrons) and the observed gamma-ray emission. Previous work in the field has suggested such a link, however the details of the interaction are not fully understood. Statistical studies on a sample of AGN have shown a delay due to optical depth effects of the order of 1.2 months in the source frame, with the gamma-ray emission leading. In this thesis studies of individual sources are presented, for which flaring events have been observed, and it is found that while optical depth can explain the time lag between flaring at different frequencies in some cases, it can not be the sole mechanism causing such a delay. Different emission sites for the radio and gamma-ray flares are proposed, to account for the properties observed. A new instrument, the single baseline interferometer CHI which can be used to quickly ascertain the compact radio flux of a gamma-ray flaring AGN is also introduced.