Observations and modeling of the active galactic nucleus B2 1215+30 together with performance studies of the ground-based gamma-ray observatories VERITAS and CTA

Ground-based gamma-ray astronomy, which provides access to photons in the TeV energy range, has been a rapidly developing discipline over the past decades. In this thesis, the performance of the current- and next-generation imaging atmospheric Cherenkov telescopes VERITAS and CTA is evaluated using Monte Carlo simulations. Special emphasis is given to the possible extension of the duty cycle of CTA. It is shown that an increase of about 30% in observation time can be achieved through operation under partial moonlight without significant losses in performance. The increased observation time is especially important when studying astronomical objects which are variable at very high energies (VHE; E>50 GeV), such as active galactic nuclei (AGN), as this allows the extension of monitoring or multi-wavelength campaigns on these occasionally flaring sources. AGN represent to date about one third of the population of known VHE gamma-ray sources. Most of them are blazars, whose emission is dominated by non-thermal radiation of relativistic jets closely aligned to the line of sight of the observer. The blazar B2 1215+30 has been observed by VERITAS for nearly 100 hours between 2008 and 2012. The data analysis presented in this thesis yields a detection significance of 9.0 sigma and shows long-term variability with a relatively bright flux state in 2011. Multi-wavelength data are used to construct the spectral energy distribution of B2 1215+30 which is well described by a one-zone leptonic model. The model is presented in detail and possible constraints are investigated. The results of the modeling are discussed and put in context with other VHE-detected blazars