Studies of active galactic nuclei with CTA
  In this paper, we review the prospects for studies of active galactic nuclei
(AGN) using the envisioned future Cherenkov Telescope Array (CTA). This review
focuses on jetted AGN, which constitute the vast majority of AGN detected at
gamma-ray energies. Future progress will be driven by the planned lower energy
threshold for very high energy (VHE) gamma-ray detections to ~10 GeV and
improved flux sensitivity compared to current-generation Cherenkov Telescope
facilities. We argue that CTA will enable substantial progress on gamma-ray
population studies by deepening existing surveys both through increased flux
sensitivity and by improving the chances of detecting a larger number of
low-frequency peaked blazars because of the lower energy threshold. More
detailed studies of the VHE gamma-ray spectral shape and variability might
furthermore yield insight into unsolved questions concerning jet formation and
composition, the acceleration of particles within relativistic jets, and the
microphysics of the radiation mechanisms leading to the observable high-energy
emission. The broad energy range covered by CTA includes energies where
gamma-rays are unaffected from absorption while propagating in the
extragalactic background light (EBL), and extends to an energy regime where VHE
spectra are strongly distorted. This will help to reduce systematic effects in
the spectra from different instruments, leading to a more reliable EBL
determination, and hence will make it possible to constrain blazar models up to
the highest energies with less ambiguity.
