The Search for Very High Energy
γ-rays from Misaligned AGN

Abstract

The aim of this work is to study the potential for emission at very high energies (100 GeV) by misaligned active galactic nuclei (AGN) and the future prospects for observations of these objects with the next generation imaging atmospheric Cherenkov telescope, the Cherenkov Telescope Array (CTA). Initially, data collected by the H.E.S.S. array was used to study fourteen Seyfert galaxies
and two other AGN with Seyfert-like properties and no new detections were reported. For each object upper limits were calculated, assuming a similar spectral shape to M87.
Further work focused on modelling the GeV spectra of misaligned AGN (AGN with angles of inclination to the line of sight 5◦ ) detected in 2010 with the Fermi Space Telescope. The modelling was carried out using a multiblob model that had previously been used to model the very high energy emission of M87 and Centaurus A. This work was used to investigate the capacity of the model to reproduce the high energy spectra observed for each object, while also allowing predictions of the potential very high energy fluxes to be produced. In each case the multiblob model was able to reproduce the observed GeV spectrum. The spectral energy distributions produced were then compared to predicted sensitivity curves for a number of possible CTA configurations to determine the likelihood of detection of these misaligned AGN with the array. It was found that detection of the objects within 50 hours of observations with CTA using standard Durham analysis is unlikely, but that 3C 111 may be detectable using the Paris analysis method.